Read each statement below carefully and state with reasons and examples, if it is true or false ;
A particle in one-dimensional motion

(a) with zero speed at an instant may have non-zero acceleration at that instant

(b) with zero speed may have non-zero velocity,

(c) with constant speed must have zero acceleration,

(d) with positive value of acceleration must be speeding up.

Question

Read each statement below carefully and state with reasons and examples, if it is true or false ;
A particle in one-dimensional motion

(a) with zero speed at an instant may have non-zero acceleration at that instant

(b) with zero speed may have non-zero velocity,

(c) with constant speed must have zero acceleration,

(d) with positive value of acceleration must be speeding up.

Philoid · Accepted Answer

(a) True.

Explanation: When an object is vertically thrown upwards, at maximum height its velocity becomes zero. However, its acceleration remains constant (acceleration due to gravity).

(b) False.

Explanation: Speed and velocity have same magnitude for a body. So, If a body is having zero speed it should have zero velocity.

(c) True.

Explanation: Acceleration is defined as change in velocity with respect to time. Thus, If change in velocity is zero acceleration is also zero.

(d) False.

Explanation: When a body is vertically thrown upwards. Even though positive acceleration the body have it will slowly speeding down due acceleration due to gravity.

True.

Explanation: When a body is freely falling from a height. Acceleration due to gravity speedup the body.