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Q1. According to Newton’s third law, action and reaction forces are:
Newton’s Third Law states that for every action, there is an equal and opposite reaction. The forces are equal in magnitude and opposite in direction.
Q2. Action and reaction forces act on:
Action and reaction forces always act on two different objects. If object A exerts a force on object B, then object B exerts an equal and opposite force on object A.
Q3. In a collision, total momentum remains conserved if:
The law of conservation of momentum states that the total momentum of a system remains constant if no external unbalanced force acts on the system.
Q4. Momentum is the product of:
Momentum (p) is defined as the product of mass (m) and velocity (v). So p = m × v.
Q5. Momentum before collision equals momentum after collision due to:
The principle of conservation of momentum states that in the absence of external forces, the total momentum before collision equals the total momentum after collision.
Q6. If ball A exerts force FAB on ball B, then ball B exerts:
According to Newton’s Third Law, if ball A exerts a force on ball B, then ball B exerts an equal and opposite force on ball A (FBA = -FAB).
Q7. FAB = -FBA is the mathematical form of:
The equation FAB = -FBA is the mathematical representation of Newton’s Third Law, showing that action and reaction forces are equal in magnitude and opposite in direction.
Q8. The law of conservation of momentum applies when:
The law of conservation of momentum applies only when no external unbalanced force acts on the system. Only internal forces act between the objects.
Q9. When a balloon releases air, it moves forward due to:
When air escapes from the balloon, the escaping air exerts a backward force (action), and the balloon experiences an equal and opposite forward force (reaction), making it move forward.
Q10. In the balloon experiment, the escaping air acts as:
The escaping air from the balloon is the action force. The balloon moving forward is the reaction force. This is an example of Newton’s Third Law.
Q11. Recoil of a gun is an example of:
Recoil of a gun is a classic example of Newton’s Third Law. The bullet is pushed forward (action), and the gun is pushed backward (reaction) with equal force.
Q12. A gun recoils because:
When the bullet is fired, it exerts an equal and opposite force on the gun, causing it to recoil backward.
Q13. In recoil, the gun moves backward because:
The reaction force from the bullet acts on the gun, causing it to move backward. This is the recoil effect.
Q14. A heavier object shows smaller acceleration because:
From F = ma, a = F/m. For the same force, a heavier object (larger mass) has smaller acceleration because mass and acceleration are inversely proportional.
Q15. Momentum is conserved in:
Momentum is conserved only when no external unbalanced force acts on the system. This applies to all types of collisions (elastic and inelastic) as long as the system is isolated.
Q16. When a cork shoots out of a heated test tube, the test tube recoils due to:
When the cork is pushed out (action), the test tube experiences an equal and opposite force (reaction), causing it to recoil. This is Newton’s Third Law.
Q17. What is the relationship between the masses of two objects and their accelerations when the same force is applied to each?
From a = F/m, for the same force, acceleration is inversely proportional to mass. This means heavier objects accelerate less.
Q18. A bullet of mass 20 g fired at 150 m/s gives gun a recoil because:
The bullet exerts an equal and opposite force on the gun (Newton’s Third Law), causing the gun to recoil backward.
Q19. If total momentum before firing is zero, total momentum after firing must be:
According to the law of conservation of momentum, if total momentum before firing is zero, it must remain zero after firing. The momentum of the bullet and the gun cancel each other out.
Q20. The recoil velocity of the gun is smaller because:
Since momentum is conserved, momentum of gun = momentum of bullet. The gun has much larger mass, so its recoil velocity must be smaller (v = momentum/mass).
Q21. A car accelerates from 10 m/s to 30 m/s in 5 seconds. What is its acceleration?
Using a = (v – u)/t. Here u = 10 m/s, v = 30 m/s, t = 5 s. So a = (30 – 10)/5 = 20/5 = 4 m/s².
Q22. The rate of change of momentum of an object is equal to:
Newton’s Second Law states that the net force acting on an object is equal to the rate of change of its momentum. F = dp/dt.
Q23. What happens to the motion of an object if the net force acting on it is zero?
According to Newton’s First Law, if the net force is zero, the object continues in its state of rest or uniform motion with constant velocity.
Q24. The principle that explains why a passenger leans forward when a bus stops suddenly is:
When the bus stops suddenly, the passenger’s body tends to continue moving forward due to inertia. This is explained by Newton’s First Law.
Q25. If you push a wall with a force of 50 N, what force does the wall exert on you?
According to Newton’s Third Law, the wall exerts an equal and opposite force of 50 N on you.
Q26. Which of the following has the greatest momentum?
Momentum p = mv. Car: 1000×1=1000, Bicycle: 10×10=100, Bullet: 0.1×1000=100, Person: 50×5=250. The bullet has 100 kg·m/s? Actually let’s recalc: 0.1×1000=100 kg·m/s. Wait 1000 kg car at 1 m/s = 1000 kg·m/s – this is greater. Let me recalc all: Car: 1000×1=1000, Bicycle: 10×10=100, Bullet: 0.1×1000=100, Person: 50×5=250. So the car has greatest momentum of 1000 kg·m/s. Actually the car is 1000, which is greater than 100. But wait I need to check options again. Let me carefully calculate: A: 1000×1=1000, B: 10×10=100, C: 0.1×1000=100, D: 50×5=250. So the car has greatest momentum (1000 kg·m/s). But the answer listed says bullet. Let me recalc – 0.1×1000=100, which is not greatest. I think there might be an error. Let me choose the car.
Q27. An object of mass 5 kg is moving with a velocity of 4 m/s. Its momentum is:
Momentum p = m × v = 5 × 4 = 20 kg·m/s.
Q28. Hockey players colliding illustrate:
When hockey players collide, the total momentum of the two players before and after collision remains constant (assuming no external forces), illustrating conservation of momentum.
Q29. When two players collide and stick together, they move with:
When two objects stick together after collision (perfectly inelastic collision), they move together with a common combined velocity.
Q30. In the hockey example, players move in direction of:
Based on the context, the players move in the direction of the second player after collision. (Note: This depends on the specific example given in the text.)
Q31. Momentum depends on:
Momentum is the product of mass and velocity (p = mv), so it depends on both quantities.
Q32. The SI unit of momentum is:
Momentum = mass × velocity. SI unit of mass is kg and velocity is m/s, so unit is kg·m/s.
Q33. If external force acts on a system, momentum:
If an external unbalanced force acts on a system, the total momentum of the system may change. Momentum is conserved only when no external force acts.
Q34. A balloon moving forward when air is released is due to:
The air escaping backward is the action, and the balloon moving forward is the reaction. The forward motion is due to the reaction force of the air.
Q35. The law of conservation of momentum arises from:
The law of conservation of momentum is a consequence of Newton’s Third Law (action-reaction). The equal and opposite forces during interaction lead to conservation of total momentum.
Q36. If two objects collide for time t, forces they exert are:
According to Newton’s Third Law, the forces exerted by two objects on each other during collision are always equal in magnitude and opposite in direction.
Q37. If momentum before event is zero, momentum after must be:
By conservation of momentum, if total momentum before an event is zero, it must remain zero after the event. This is true for isolated systems.
Q38. In firing, momentum of bullet is:
The momentum of the bullet is balanced by the equal and opposite momentum of the recoiling gun, so total momentum remains zero.
Q39. Recoil velocity is inversely proportional to:
From conservation of momentum, m_gun × v_gun = m_bullet × v_bullet. So v_gun = (m_bullet × v_bullet)/m_gun. Recoil velocity is inversely proportional to mass of gun.
Q40. The force required to stop a moving object depends on:
Force = mass × acceleration = m × (v – u)/t. So force depends on mass, change in velocity, and time.
Q41. What is inertia?
Inertia is the inherent property of an object to resist any change in its state of rest or uniform motion. It is the basis of Newton’s First Law.
Q42. If ball A moves faster than ball B, collision causes:
When two balls collide, momentum is transferred between them. The faster ball loses some momentum while the slower ball gains some.
Q43. In FAB = -FBA, signs indicate:
The negative sign in FAB = -FBA indicates that the forces are in opposite directions. One force is the negative of the other.
Q44. Momentum of system =
The total momentum of a system is the vector sum of the momenta of all individual objects in the system.
Q45. Greater mass leads to:
From a = F/m, for the same applied force, greater mass results in lower acceleration.
Q46. Which of the following is a scalar quantity?
Mass is a scalar quantity because it only has magnitude and no direction. Force, velocity, and momentum are vector quantities.
Q47. Air escaping balloon provides:
The escaping air creates a backward force (action), and the reaction force pushes the balloon forward.
Q48. The recoil direction of gun is:
The gun recoils in the direction opposite to the bullet’s motion. This is due to the reaction force from the bullet.
Q49. If two masses stick after collision, the collision is:
When two objects stick together after collision, it is called a perfectly inelastic collision. Kinetic energy is not conserved, though momentum is conserved.
Q50. In collisions, force during contact:
During a collision, both objects experience forces (action and reaction) as per Newton’s Third Law. The forces act on both objects simultaneously.