Question

Assertion - Reason Questions
(i) Both A and R are true and R is correct explanation of the assertion.
(ii) Both A and R are true but R is not the correct explanation of the assertion.
(iii) A is true but R is false.
(iv) A is false but R is true.
1. Assertion: A ball thrown vertically upwards has zero momentum.
Reason: Velocity of ball is zero at its highest point of motion.
2. Assertion: An athlete comes running from a distance, he is able to jump longer.
Reason: He does not gain momentum.
3. Assertion: The velocity of an object is decreasing with passage of time.
Reason: The acceleration is negative.

Answer 1

Explanation:

1) When a body is thrown vertically upwards, at the highest point only velocity is zero because the acceleration due to gravitational force is acting downward continuously and that is the reason for velocity being zero at the highest point, hence velocity is zero because of the acceleration.

2) An athlete runs before jumping to gain momentum because it helps in jumping higher and longer because of the inertia of motion gained due to motion. When the athletes jump, they already have a forward motion that would be greater than that of a jump made from standing in one spot

3) option 2