Question

An object travels north with a velocity of $10\, ms^{- 1 }$ and then speeds up to a velocity of $25 \, ms^{-1}$ in 5 s. The acceleration of the object in these 5 s is

• A. $12 \,m$ $s ^{-2}$ in north direction
• B. $3 \,m$ $s ^{-2}$ in north direction
• C. $15\, m$ $s ^{-2}$ in north direction
• D. $3\, m$ $s ^{-2}$ in north direction

Answer 1

Answer: (B)

Acceleration a =$\frac{\Delta t}{\Delta t}=\frac{v_2 -v_1}{\Delta t}$
Given v, = $10 ms^{-1} ,v_2 = 25 ms^{-1}, \Delta t = 5s$
hence $a=\frac{25-10}{5} 3ms^{-2}$in north direction.