Question

A man in a sled, with a total mass of 125 kg, slides down a grassy hill and reaches a speed of 8 m/s at the bottom. If a pile of grass can exert a constant force of 250 N, how fast will the sled stop?

Answer 1

Explanations & Calculations

$\qquad\qquad \begin{aligned} \small F&=\small ma\\ \small a&=\small \frac{250\,N}{125\,kg}=2\,ms^{-2}\\ \\ \small F&=\small \frac{m(v-u)}{\Delta t}\\ \small \Delta t&=\small \frac{125\,kg(0-8)}{-250\,N}\\ &=\small 4\,s \end{aligned}$

• He would come to rest at a deceleration of 2m/s^s for 4 seconds.