Question

A man is moving on his bike with $54km{h}^{-1}$. He takes a U turn in $10s$ and continues to move with the same velocity. Find average acceleration during this time.

• A. $-3.0m{s}^{-2}$
• B. $1.5m{s}^{-2}$
• C. $3.0m{s}^{-2}$
• D. $-1.5m{s}^{-2}$

Answer 1

The correct option is A $-3.0m{s}^{-2}$

A man moves on his bike say in X direction with $15m{s}^{-1}$,
$\therefore \overrightarrow{v_1}=15i$
He takes a U-turn and continues to move with the same velocity,
$\therefore \overrightarrow{v_2}=-15i$
Total time taken $=10s$
$\therefore a_{avg}=\frac{\overrightarrow{v_2}-\overrightarrow{v_1}}{t}$

$\therefore a_{avg}=\frac{-15\hat{i}-\left(15\hat{i}\right)}{10}$

$\therefore a_{avg}=-3\hat{i}$
$\therefore a_{avg}=-3m{s}^{-2}$