Question

A body is moving vertically upwards. Its velocity changes at a constant rate from $50m{s}^{-1}$ to $20m{s}^{-1}$ in $3s$. What is its acceleration?

• A. $10m{s}^{-2}$
• B. $-10m{s}^{-2}$
• C. $1m{s}^{-2}$
• D. $-1m{s}^{-2}$

Answer 1

The correct option is B $-10m{s}^{-2}$

Initial velocity $=50m{s}^{-1}$
Final velocity $=20m{s}^{-1}$
Time $=3s$
Acceleration = $\frac{20-50}{3}$ m$s^{-2}$ $=-10m{s}^{-2}$