1. The S.I. unit of force is
I. Kgm/s
II. Kgm/s2
III. Newton
IV. Newton-meter
2. What do we get by the product of mass and velocity?
I. Force
II. Inertia
III. Momentum
IV. Newton
3. The rate of change of momentum of an object is proportional to
I. Mass of the body
II. Velocity of the body
III. Net force applied on the body
IV. None of these
4. If two balls of same masses are dropped on sand, the depths of penetration is same if
I. Heavier ball is dropped faster than lighter ball
II. Lighter ball is dropped faster than heavier ball
III. The product ‘mv’ is same for both bodies
IV. None of these
5. A coin placed on a card(rested at the edges of the glass) remains at rest because of
I. Inertia of rest
II. Two forces act on the coin which balance each other
III. No unbalanced force acts on it
IV. All of these
6. A force of 50N moves a body,
I. Friction force exerted on the body is less than 50N
II. Friction force exerted on the body is more than 50N
III. None of these
IV. Both of I and II
7. A fielder giving a swing while catching a ball is an example of
I. Inertia
II. Momentum
III. Newton’s II law of motion
IV. Newton’s I law of motion
8. Action and reaction forces
I. Act on the same body
II. Act on different bodies
III. Act in same direction
IV. Both I and III
9. When we pedaling the bicycle it stops because
I. The earth’s gravitational force acts on it
II. It is not accelerated
III. No unbalanced force acts on it
IV. Frictional force acts on it
10. A football and a stone has same mass
I. Both have same inertia
II. Both have same momentum
III. Both have different inertia
IV. Both have different momentum
1. State two effects of force.
2. Scientist who first conducted experiment to form the base for Newton's first law of motion.
3. If first law of motion holds true, why does a ball rolling on ground stop on its own?
4. What would happen if there was no friction on the Earth?
5. What would happen if gravitational force of the Sun suddenly vanishes?
6. What did Galileo observe by placing two inclined planes facing each other and rolling down a marble ball from top end of one of them?
7. What is the negative effect of friction on your shoe soles?
8. You are applying force on the pan of single pan weighing balance and the pointer points to 100 g. What is the force in newtons applied by you?
9. An athlete always runs some distance before taking a jump. Why?
10. A cricket ball of mass 70 g moving with a velocity of 0.5 m/s is stopped by a player in 0.5 s. What is the force applied by the player to stop the ball?
11. In a cricket match, why does a player lower his hands slightly while catching the ball?
12. Two cars having masses in the ratio 4 : 5, accelerate in the ratio 2:3. Find the ratio o forces exerted by each of them.
1. What do you mean by law of conservation of momentum?
2. Why do roads on mountains have inward inclination at sharp turns?
3. Why is it dangerous to jump out of a moving bus?
4. How do safety belts of cars help in preventing accidents?
5. Explain how momentum gets conserved in collision of two bodies?
6. How are Newton�s three laws of motion related?
7. Explain inertia and momentum in detail.
8. Define force and its various types. What is its unit?
9. Give three examples exhibiting inertia in our daily life
10. What change will a force bring in a body?
11. From a rifle of mass 5kg, a bullet of mass 50gram is fired with an initial velocity of 50m/s. Calculate the initial recoil velocity of the rifle.
12. Explain how Newton�s second law of motion is used in sports?
13. Why does one get hurt on jumping from a great height to the floor?
14. What is a balanced force?
Max Time:30 mins
Max Marks:25
1. Why do passengers tend to fall sideways when the bus takes a sharp u turn? (2 marks)
2. Why should a passenger hold on to prevent himself from swaying in a turning bus? (2 marks)
3. Why do passengers tend to fall back when it starts suddenly? (2 marks)
4. Why do passengers jumping out of a rapidly moving bus fall forward with his face downwards, if he does not run forward? (2 marks)
5. Why does a passenger jumping out of a rapidly moving bus fall forward with his face downwards? (2 marks)
6. Why can dust be removed by shaking it, or beating it by a carpet? (2 marks)
7. Why does a bullet when fired against a glass window pane make a hole in it, and the glass pane will smash it? (2 marks)
8. Why does an athlete take a longer jump if he comes running from a distance than when he jumps suddenly from the take-off line? (2 marks)
9. What happens when you shake a wet piece of cloth? Explain, why? (2 marks)
10. Why is it advised to tie a rope on the luggage while you travel by the bus? (2 marks)
11. How does a boat move forward into the water when the boatman presses one end of the pole against the ground? (2 marks)
12. Why is it difficult for a fireman to hose, which ejects large amount of water at a high velocity? (3 marks)