Friday 9 September 2016

Physics Questions

Section – A

1.             The driver of train A travelling at a speed of 54 kmh-1 applies brakes and retards the train uniformly. The train stops in 5 seconds. Another train B is travelling on the parallel with a speed of 36 kmh-1. Its driver applies the brakes and the train retards uniformly; train B  stops in 10seconds.
Plot speed-time graphs for both the trains on the same axis. Which of the trains travelled farther after the brakes were applied?
2.             State which of the following situations are possible and give an example for each of these: (a) an object with a constant acceleration but with zero velocity (b) an object moving in a certain direction with an acceleration in the perpendicular direction.
3.             An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be
the distance covered and the displacement at the end of 2 minutes and 20 seconds?
4. .              The velocity of a body in motion is recorded every second as shown-
time(s)

0


2

3

4

5

6

7

8

9

10

Velocity(m/s)

62

54

48

42

36

30

24

18

12

6

0



Calculate the

(a) Acceleration (b) distance travelled and draw the graph.

6.             Which law of motion gives the measure of force?
7.             Define 1 newton force.
8.             Name the principle on which a rocket works.
9.             State Newton’s third law of motion and how does it explain the walking of man on the

ground?
10.          When small boy is trying to push a heavy stone, mention various forces acting on the
stone.
11.          A 8000 kg engine pulls a train of 5 wagons, each of 2000 kg, along a horizontal track. If the engine exerts a force of 40000 N and the track offers a friction force of 5000 N, then calculate:
(a)  the net accelerating force;
(b)  the acceleration of the train; and
(c) the force of wagon 1 on wagon 2.
12.          Derive the second equation of motion  S ut 1 at2    graphically?
13.          Why does a person while firing a bullet holds the gun tightly to his shoulders?
14.          Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?
15.          Derive the third equation of motion- v2-u2=2aS
16.     Why does an athlete puts some sands or cushion on the ground while high jumping?
17.          State Newton’s second law of motion and derive it mathematically?



18.          Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?
19.          Differentiate between mass and weight?
20.          The radius of earth is 6370Km and of mars is 3400 Km. If an object weighs 200N or earth, what will be its weight on mars. The mass of mars is 0.11 that of earth.
21.          Derive expression for force of attraction between two bodies and then define gravitational constant.
22.          What is the magnitude of the gravitational force between the earth and a 1 kg object on its surface?

(Mass of the earth is 6 1024 kg and radius of the earth is 6.4 106 .)

23.          How does the weight of an object vary with respect to mass and radius of the earth? In a

hypothetical case, if the diameter of the earth becomes half of its present value and its mass

becomes four times of its present value, then how would the weight of any object on the

surface of the earth be affected?
 
24.          Show that the weight of an object on the moon is 6thof its weight on the earth..


25.        A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate

of 10 m s-2, with what velocity will it strike the ground? After what time will it strike the

ground?


26.          A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate the maximum

height to which it rises.



27.          On the earth, a stone is thrown from a height in a direction parallel to the earths surface

while another stone is simultaneously dropped from the same height. Which stone would

reach the ground first and why?
28.          State the factors on which acceleration due to gravity (g) depends?

29.          Define electrostatic force.

30.          Calculate the force of gravitation between the earth and the Sun, given that the mass of the

earth = 6 1024 kg and of the Sun = 2 1030 kg. The average distance between the two is

1.5 1011m.

31.          Why do you fall in the forward direction when a moving bus brakes to a stop and fall

backwards when it accelerates from rest?
32.          Prove that if a body is thrown vertically upward, the time of ascent is equal to the time of

descent.

33.          A ball thrown up vertically returns to the thrower after 6 s. Find

(a) the velocity with which it was thrown up.

(b) the maximum height it reaches, and


(c) its position after 4s.

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