Question

A cart is released from rest at the top of a long ramp at time $t=0$ seconds and moves down the ramp at a constant acceleration rate. At a time of t, the cart has reached a speed of $2m/s$. How fast will the cart be moving at the time of $3t$?

• A. $3m/s$
• B. $6m/s$
• C. $12m/s$
• D. $18m/s$

Answer 1

Answer: (B)

$6m/s$

Initial speed of the cart $u=0$ m/s

Speed of cart after time $t$ $v=2$ m/s

Using $v=u+at$

$\therefore$ $2=0+at$ $⟹at=2$

Speed of cart at the instant $3t$ $v^{\prime }=u+a{t}^{\prime }$ where $t^{\prime }=3t$

$\therefore$ $v^{\prime }=0+a\left(3t\right)=0+3\times 2=6$ m/s