Download force and laws of motion

INDIAN SCHOOL AL WADI AL KABIR
WORKSHEET-CLASS-9-PHYSICS
FORCE AND LAWS OF MOTION
1. State any three changes that a force bring about in a body.
2. When are the forces acting on a body said to be balanced? give an example .What
type of change can the balanced forces bring about in an object?
3. A ball is moving over a horizontal smooth surface with a constant velocity. what type
of forces are acting on the ball?
4. State Newton’s first law of motion .Explain it with the help of suitable examples.
5. Describe in brief an activity to illustrate the property of inertia of rest.
6. Define the term inertia. what are the different types of inertia?
7. Name the property of bodies to resist a change in their velocities.
8. On what factor does the inertia of a body depend. Explain with the help of a suitable
example.
9. There are three solid balls, made up of aluminium, steel and wood of the same shape
and volume. Which of them would have highest inertia? why?
10.Why do we jerk wet clothes before spreading them on string?
11.It is dangerous to jump out of a moving bus. why?
12.What does a bowler tend to gain during running from a long distance before he
bowls from the takeoff line?
13.Name the unbalanced force which slows down a moving bicycle when we stop
pedaling it.
14.A bullet fired against a window glass pane makes a hole in it and the glass pane is not
cracked. On the other hand a stone striking the same glass pane will smash it.Explain
why?
15.Name the force that keeps the object moving in a circular path with constant
acceleration. What would happen if this force is absent?
16.State the Newton’s second law of motion. give its mathematical expression. Define
the SI unit of force.
17.While playing football the goalkeeper didn’t get sufficient time to stop a fast ball shot
towards him. why did he hurt his hand while doing so?
18.A man throws a ball of mass 0.5 kg vertically upwards with a velocity of 10m/s. What
will be its initial momentum? What would be its momentum at the highest point of
its reach?
19.A steam engine of mass 3x104kg pulls two wagons each of mass 2x104kg with an
acceleration of 0.2m/s2 .Neglecting frictional force, calculate the
(i)
Force exerted by the engine
(ii)
Force experienced by each wagon.
20.A car of mass 1000kg moving with a velocity of 45km/h collides with a tree and
comes to a stop in 5s.Waht will be the force exerted by the car on the tree?
21.A force of 0.6 N acting on a body increases its velocity from 5m/s to 6m/s in 2s.
Calculate the mass of the body.
22.For how much time should the force of 400N be exerted on a body of mass 8kg to
increase its velocity from 150m/s to300m/s
23.When a man jumps out from a boat, the boat moves backwards. why?
24.Action and reaction are equal and opposite but even then they do not cancel each
other. Give reason.
25.State the law of conservation of momentum. prove this law by taking the case of
collision of two bodies.
26.A bird hit the windscreen of a fast moving car and fells on the bonnet. which of the
two, car or the bird suffers the greater change in momentum.
27.A bullet of mass 20g moving with a speed of 500m/s strikes a wooden block of mass
1kg and gets embedded in it. Find the speed with which block moves along with the
bullet.
28.A body of mass 2kg initially moving with a velocity of 10m/s collides with another
body of mass 5kg at rest. After collision velocity of first body becomes 1m/s. Find the
velocity of the first body.
29.A body of mass 60kg running at 3m/s jumps on to a trolley of mass 140kg moving
with a velocity of 1.5m/s in the same direction. What is their common velocity?
30.An object of mass 200kg is accelerated uniformly from a velocity of 10m/s to 20m/s
in 2 s. calculate (i) initial momentum. (ii) final momentum of the object and
(iii)
magnitude of the force exerted on the object.
Prepared by Asha John