MCQ
The same retarding force is applied to stop a train. The train stops after $80\, m$. If the speed is doubled, then the stopping distance will be
- AThe same
- BDoubled
- CHalved
- ✓Four times
✓
Answer
Correct option: D.
Four times
d
$\mathrm{v}^{2}=2 \mathrm{aS}$
$\mathrm{v}^{2}=2 \mathrm{aS}$
$\mathrm{v}_{1}^{2}=2 \times \mathrm{a} \times 80, \mathrm{v}_{2}^{2}=4 \mathrm{v}_{1}^{2}$
$2 \mathrm{aS}=4 \times 2 \mathrm{a} \times 80 \Rightarrow \mathrm{S}=320$
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