Question

Read each statement below carefully and state with reasons and examples, if it is true or false;

A particle in one-dimensional motion with positive value of acceleration mustbe speeding up.

Answer 1

This statement is false in the situation when acceleration is positive and velocity is negative at the instant time taken as origin. Then, for all the time before velocity becomes zero, there is slowing down of the particle. Such a case happens when a particle is projected upwards.

This statement is true when both velocity and acceleration are positive, at the instant time taken as origin. Such a case happens when a particle is moving with positive acceleration or falling vertically downwards from a height.