Displacement sums
1.find Distance and displacement when body covers full circle of radius 7cms
2.find Distance and displacement when body covers half circle of radius 7cms
3..find Distance and displacement when body covers quarter circle of radius 7cms
4.find Distance and displacement when body covers full circle of radius 7cms 2 times
5..find Distance and displacement when body covers full circle of radius 7cms 3 times
6.find distance and displacement if body move 3km south and 4km east .
7.find distance and displacement if body move 12km south and 5km east .
7.find Distance and displacement when body covers 10km south 5km east and 20 km south again
8.find Distance and displacement when body covers 15km south 10km east and 25 km south again
9.find distance and displacement when body covers 10km south 20 km east and 30 km north
10.find distance and displacement when body covers 15km south 20 km east and 25 km north
10.find distance and displacement when body covers 5 km south 10km east and 5km north
11.find distance and displacement when body covers 10 km south 20km east and 10km north
12.
Saturday 22 May 2021
Thursday 20 May 2021
distance topic explained with numericals to practice for all classes
Distance sums
Distance =speed x time
This formula applicable for uniform speed only
1.find Distance travelled by body moving with 10 m/s in 2 sec
2.find Distance travelled by body moving with 2 kmph in 2 hrs
3.find Distance travellen by body moving with 2m/s in 2 mins
4.find Distance travelled by body moving with 10 m/s in 3 hrs
5.find Distance traveled by body moving with 60 kmph in 1min
6 find Distance traveled by body moving with 120kmph in 2 hrs
7.find Distance travelled by body moving with 3600 m/s on 1 hr
8.find speed when body travelled 100m in 2 sec
9.find speed when body travelled 2km in 2 hrs
10.find time when body moving with 200 m/s covers 20 m
10.find time in which body moving with 200 kmph covers 4 km
11.find Distance covered if body moves with speed of 10 m/s for 2 hrs
12.find Distance covered if body moves with 200cm/s for 2 sec
13.find speed if body covers 200 cm in 2 sec
14.find time in which body covers 2000cm in 2 cm/s
15.find Distance covered if body moved with speed of 20 m/s in in 1 min
16.find time in which body covers 2km with speed of 60kmph
17. A train 150m
long is running at a uniform speed of 90km/ hr. Find:
i) The time taken by it to cross a man standing on the platform.
ii) The time taken by it to cross a platform of 300m.
18.Question 2: A train 280
m long is running at a uniform speed, of
63km / hr. Find:
i) The time taken by it to cross a telephonic pole.
ii) The time taken by it to cross a bridge 210 m long.
19.Question 3: A train 180
m long passes a telegraph post in 12 seconds
. Find:i) Its speed in km/hr.
ii) The time taken by it to pass a platform 135m long
20. With a speed of 60km/hr, a train crosses a pole in 24 sec.Find the length of the train.
21.A train 700m long is running at 72km/hr. If it crosses a tunnel in one minute, find the length of the tunnel.
22.Question 6: A train 270m long takes 20sec to cross a bridge 330 m long. Find:
A.The speed of the train in km/hr
B.Time taken by it to cross an electric pole.
23.Question 9: Two cars are 351 km apart. They start at the same time and drive towards each other. One travels at 70km/hr and the other travels at 65km/hr. How much time do they take to meet each other?
24.: A train 120m long, travelling at 45km/hr, overtakes another train travelling in the same direction at 36km/hr and passes it completely in 80sec
. Find the length of the second train.
25: The speed of a boat in still water is 8
km/hr and the speed of the stream is 2.5
km/hr Find:
i) The time taken by the boat to go
km downstream
1i) The time taken by the boat to go 22 km, upstream.63
26.A stream is flowing at 3km/hr. A boat with a speed of 10km/hr in still water is rowed upstream for 13hours. Find the distance rowed. How long will it take to return to the starting point?
27.The speed of a boat in still water is 10 km/hr. It is rowed upstream for a distance of
45km in 6hours. Find the speestream.
28.Question 18: A stream is flowing at
4.8kmhr.boatcanrowdownstram for a distance of
49km in 3.5hours. Find the speed of the boat in still water
29.The speed of a boat in still water is .
5 km/hr and the speed of the stream is 1 km/hr. The boat is rowed upstream for a certain distance and taken back to the starting point. Find the average speed for the whole journey.
30.The speed of a boat downstream is 16
km/hr and its speed upstream is 10
km/hr. Find the speed of the boat in still water and the rate of the stream.
30. Find speed when, distance is 142 km and time is 2 hours.
31. Find out the distance covered when, speed is 960 km/hour and time is 1 hour 50 minutes.
32. Determine the time taken when, distance is 7150 km and speed is 780 km/hr.
33. If distance travelled by a train is 495 km in 4 hours 30 minutes, what is its speed?
34. A cyclist covers 950 m in 5 minutes. Find his speed in km/ hour.
35 The speed of the train is 72 km per hour. Find its speed in metre per second.
36 Express the speed of 60 m per minute in km per hour.
37. A man runs at the speed of 10 km/hr. How much time will he take to cover 750 metres?
38. Aaron ran 500 metre in 100 Seconds. Find the speed in km per hour.
39 A cyclist travels at a speed of 20 km/hour. How far will he travels in 50 minutes?
40.
A car drives with a constant speed of 78 miles per hour. How long will it take to travel a distance of 117 miles?
41aA taxi hurries with a constant speed of 116 km/h. How far can it travel in 3 1/2 hours?
42.
An airplane flies with a constant speed of 640 km/h. How long will it take to travel a distance of 2240 kilometers?
43.Pete roller skates with a constant speed of 16 km/h. How far can he travel in 1/2 hour?
44.
An airplane flies with a constant speed of 640 km/h. How far can it travel in 2 hours
45.An airplane flies with a constant speed of 700 miles per hour. How far can it travel in 3 hours?
46.
An airplane flies with a constant speed of 1056 km/h. How long will it take to travel a distance of 4664 kilometers?
47..Caleb rides his motorcycle with a constant speed of 60 km/h. How long will he take to travel a distance of 40 kilometers?
48..An airplane flies 2520 km in 2 hours 20 minutes. What is its average speed in kilometers per hour?
49.Caleb rides his horse with a constant speed of 12 miles per hour. How long will he take to travel a distance of 42 miles?
50.Sarah rides her bike with a constant speed of 12 miles per hour. How far can she travel in 3 2/3 hours?
51.Julia drives her car 72 km in 2 hours. What is her average speed in kilometers per hour?
52.John rides his horse 28 km in 1 hour 45 minutes. What is his average speed in kilometers per hour?
53.A minibus drives with a constant speed of 36 km/h. How far can it travel in 3 hours 15 minutes?
54.Nancy rides her bike with a constant speed of 16 miles per hour. How long will she take to travel a distance of 52 miles?
55.Pete roller skates 52 miles in 3 1/4 hours. What is his average speed in miles per hour?
56.An airplane flies with a constant speed of 700 miles per hour. How long will it take to travel a distance of 175 miles?
57.Abigail rides her bike with a constant speed of 12 km/h. How long will she take to travel a distance of 40 kilometers?
58.Emily roller skates 20 miles in 2 hours. What is her average speed in miles per hour?
59.Mike rides his horse with a constant speed of 6 miles per hour. How long will he take to travel a distance of 3 miles?
60.A taxi hurries with a constant speed of 104 km/h. How far can it travel in 3 1/2 hours?
61.Caleb rides his bike with a constant speed of 6 miles per hour. How long will he take to travel a distance of 3 miles?
62.A taxi hurries with a constant speed of 56 miles per hour. How far can it travel in 4 hours?
63.Mary rides her horse with a constant speed of 16 km/h. How long will she take to travel a distance of 64 kilometers?
Thursday 6 May 2021
power of lens notes and so many numericals to practice 10th class with video link
Video link
https://youtu.be/oYoNWFOddYc
Power of lens notes and numericals to practice
notes
power definition
capacity of lens to converge or diverge light rays passing through it
compulsory draw diagram
units are dioptres
formula
power =1/ f. in m. or 100/f in cm
I dioptre or define unit of power
1 diopter is power of lens whose focal length is 1 m or 100 cms
power of combination p= p1. + p2. + p3 ..........
power of convex. lens positive
power of concave lens is negative
numericals to practice
1.Two thin lense of power+3.5D and -2.5D are kept in contact.find the power and focal length of combination and its nature.
2.A convex lens of powerl length 25cm and concave lens of focal lenth 10cms are placed in contact what is nature ,power and focal length of combination
3.the power of combination of two lenses x and y is +5D.the focal lengtj of combination of lens x is 14cm.state the nature and focale length of lens y.
4.how are power and focal length of lenses are related.you are provided with two thin lenses of ficale length 20cm and 40 cm respectively.which lens will use to produce more convergent light.
5 a convex lens has focal length of 10cm.what is its power
6.A student uses lens of focal length 50 cm and another of -50 cm.what is the nature and its power used by each of them
7.two thin lenses of focal length +10cm and
-5cms are kept in contact with each other what is the focal length of its combination
8.power of combination of two lenses is +2.5 D and focal length of one is -20 cm what is foclalength and nature of other lens
9.fical length of combination of 2 lens is +20cm and power of one it is -5D find the power of other lens and its nature
10. three lenses of focal length are 10cm -20cm and -25cm.what is power of combination this 3 lenses
11.what happens if lens is dipped in water
ans.
When a lens is dipped in water its focal length increases
. Focal length is inversely proportional to magnification power (angular magnification), hence
power decrease
with the increasing wavelength.
12.what happens to focal length when mirror is dipped in water
ans.
no change it remains same
13.which has more focal length thin or thick lens
ans.
thin lens has more focal length
hence less power
as power is inversely proportional to focal length
14.the power if concave lens is 2.5 D .find the focal length of lens
15..find power of concave lens of focal length 2m
16..find the focal length of lens of power -2D.
17..two lenses of power +2.5 D and -0.5D aare kept in contact.what is the power of combination and focal length of combination.
18..two lenses of power +3.5D and - 2.5 D are placed in contact. what is power and focal length of combination
19.a convex and concave lens of focal length 50 cm and 40 cm.are placed in contact find power and focal length of combination
20. a combination of convex and concave lens has power +2 D.if the focal length of convex lens is 25 cm.find the focal length of concave lens used in the combination.
21.a convex lens has fl. 10cm.find the power
22.a student has lenses if fl +50cm and another of fl.-50 cms.what are nature of each and power of each lens.and power of combination
23.two thin lenses of fl.19cm and -5cm are kept in contact t.what is fl and power of combination.
24.you are given lenses with power 10D,5D,-20F,and -10D.taking a pair of lenses at a time.which two lenses will you select to have a combination of total fl. when the two lenses are kept in contacting each case.
a.20cm
b.-10cm
c.-20cm
d.20/3 cm.
25.power of lens is +4D.what kind of lens is it and find its fl
26.a lens has fl 10cm.what is the power of lens and its nature
27.the power of lens is-2D.what is its fl and nature
28.focal length of lens in photographic camera is 5cm.find the power of lens
29.two lenses of power 3D and -5D are kept in contact to form a composite lens.an object is kept at a distance of 50 cms from this composite lens.find the position of image
30..tow lenses of fl 10cm and -10cm respectively.find nature and power of both the lenses.which of this two lenses will form virtual and magnified image of an object placed at 8cm from the lens.draw ray diagram to justify your answer.
31.the power of lens is 5D.what is nature and fl of lens.where should object from this lens to be place to get image of same size.justify with ray daigram
32.how does the power of lens change if the fl is doubled.
33.which lens has more power thick or thin lens.
34.find the power of lens of concave lens of fl 20cm.
35.find the fl of convex lens is 25cm.express power with sign convention
36..(2020model paper)
Refractive index of water with respect to air is 1.33 and that of diamond is
2.42.
(i) In which medium does the light move faster, water or diamond?
(ii) What is the refractive index of diamond with respect to water?
1.Two thin lense of power+3.5D and -2.5D are kept in contact.find the power and focal length of combination and its nature.
37.A convex lens of focal length 25cm and concave lens of focal lenth 10cms are placed in contact what is nature ,power and focal length of combination
38..the power of combination of two lenses x and y is +5D.the focal lengtj of combination of lens x is 14cm.state the nature and focale length of lens y.
39..how are power and focal length of lenses are related.you are provided with two thin lenses of ficale length 20cm and 40 cm respectively.which lens will use to produce more convergent light.
40. a convex lens has focal length of 10cm.what is its power
41.A student uses lens of focal length 50 cm and another of -50 cm.what is the nature and its power used by each of them
42.two thin lenses of focal length +10cm and
-5cms are kept in contact with each other what is the focal length of its combination
43.power of combination of two lenses is +2.5 D and focal length of one is -20 cm what is foclalength and nature of other lens
44.fical length of combination of 2 lens is +20cm and power of one it is -5D find the power of other lens and its nature
45. three lenses of focal length are 10cm -20cm and -25cm.what is power of combination of this 3 lenses and also find its focal length of combination and also nature of combination
notes
power definition
capacity of lens to converge or diverge light rays passing through it
compulsory draw diagram
units are dioptres
formula
power =1/ f. in m. or 100/f in cm
I dioptre or define unit of power
1 diopter is power of lens whose focal length is 1 m or 100 cms
power of combination p= p1. + p2. + p3 ..........
power of convex. lens positive
power of concave lens is negative
numericals to practice
1.Two thin lense of power+3.5D and -2.5D are kept in contact.find the power and focal length of combination and its nature.
2.A convex lens of powerl length 25cm and concave lens of focal lenth 10cms are placed in contact what is nature ,power and focal length of combination
3.the power of combination of two lenses x and y is +5D.the focal lengtj of combination of lens x is 14cm.state the nature and focale length of lens y.
4.how are power and focal length of lenses are related.you are provided with two thin lenses of ficale length 20cm and 40 cm respectively.which lens will use to produce more convergent light.
5 a convex lens has focal length of 10cm.what is its power
6.A student uses lens of focal length 50 cm and another of -50 cm.what is the nature and its power used by each of them
7.two thin lenses of focal length +10cm and
-5cms are kept in contact with each other what is the focal length of its combination
8.power of combination of two lenses is +2.5 D and focal length of one is -20 cm what is foclalength and nature of other lens
9.fical length of combination of 2 lens is +20cm and power of one it is -5D find the power of other lens and its nature
10. three lenses of focal length are 10cm -20cm and -25cm.what is power of combination this 3 lenses
11.what happens if lens is dipped in water
ans.
When a lens is dipped in water its focal length increases
. Focal length is inversely proportional to magnification power (angular magnification), hence
power decrease
with the increasing wavelength.
12.what happens to focal length when mirror is dipped in water
ans.
no change it remains same
13.which has more focal length thin or thick lens
ans.
thin lens has more focal length
hence less power
as power is inversely proportional to focal length
14.the power if concave lens is 2.5 D .find the focal length of lens
15..find power of concave lens of focal length 2m
16..find the focal length of lens of power -2D.
17..two lenses of power +2.5 D and -0.5D aare kept in contact.what is the power of combination and focal length of combination.
18..two lenses of power +3.5D and - 2.5 D are placed in contact. what is power and focal length of combination
19.a convex and concave lens of focal length 50 cm and 40 cm.are placed in contact find power and focal length of combination
20. a combination of convex and concave lens has power +2 D.if the focal length of convex lens is 25 cm.find the focal length of concave lens used in the combination.
21.a convex lens has fl. 10cm.find the power
22.a student has lenses if fl +50cm and another of fl.-50 cms.what are nature of each and power of each lens.and power of combination
23.two thin lenses of fl.19cm and -5cm are kept in contact t.what is fl and power of combination.
24.you are given lenses with power 10D,5D,-20F,and -10D.taking a pair of lenses at a time.which two lenses will you select to have a combination of total fl. when the two lenses are kept in contacting each case.
a.20cm
b.-10cm
c.-20cm
d.20/3 cm.
25.power of lens is +4D.what kind of lens is it and find its fl
26.a lens has fl 10cm.what is the power of lens and its nature
27.the power of lens is-2D.what is its fl and nature
28.focal length of lens in photographic camera is 5cm.find the power of lens
29.two lenses of power 3D and -5D are kept in contact to form a composite lens.an object is kept at a distance of 50 cms from this composite lens.find the position of image
30..tow lenses of fl 10cm and -10cm respectively.find nature and power of both the lenses.which of this two lenses will form virtual and magnified image of an object placed at 8cm from the lens.draw ray diagram to justify your answer.
31.the power of lens is 5D.what is nature and fl of lens.where should object from this lens to be place to get image of same size.justify with ray daigram
32.how does the power of lens change if the fl is doubled.
33.which lens has more power thick or thin lens.
34.find the power of lens of concave lens of fl 20cm.
35.find the fl of convex lens is 25cm.express power with sign convention
36..(2020model paper)
Refractive index of water with respect to air is 1.33 and that of diamond is
2.42.
(i) In which medium does the light move faster, water or diamond?
(ii) What is the refractive index of diamond with respect to water?
1.Two thin lense of power+3.5D and -2.5D are kept in contact.find the power and focal length of combination and its nature.
37.A convex lens of focal length 25cm and concave lens of focal lenth 10cms are placed in contact what is nature ,power and focal length of combination
38..the power of combination of two lenses x and y is +5D.the focal lengtj of combination of lens x is 14cm.state the nature and focale length of lens y.
39..how are power and focal length of lenses are related.you are provided with two thin lenses of ficale length 20cm and 40 cm respectively.which lens will use to produce more convergent light.
40. a convex lens has focal length of 10cm.what is its power
41.A student uses lens of focal length 50 cm and another of -50 cm.what is the nature and its power used by each of them
42.two thin lenses of focal length +10cm and
-5cms are kept in contact with each other what is the focal length of its combination
43.power of combination of two lenses is +2.5 D and focal length of one is -20 cm what is foclalength and nature of other lens
44.fical length of combination of 2 lens is +20cm and power of one it is -5D find the power of other lens and its nature
45. three lenses of focal length are 10cm -20cm and -25cm.what is power of combination of this 3 lenses and also find its focal length of combination and also nature of combination
46.
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