Question

question 13 of 25
john coasts on his skateboard at a speed of 1 m/s. he uses his foot to increase his speed to 3 m/s. if he has a mass of 95 kg, what impulse does he apply?

a. 95 kg·m/s
b. 145 kg·m/s
c. 285 kg·m/s
d. 190 kg·m/s

Explanation:

Step1: Recall impulse - momentum theorem

Impulse $J=\Delta p$, where $\Delta p = m\Delta v$.

Step2: Calculate the change in velocity

$\Delta v=v_f - v_i$, with $v_i = 1\ m/s$ and $v_f=3\ m/s$. So $\Delta v=3 - 1=2\ m/s$.

Step3: Calculate the impulse

Given $m = 95\ kg$ and $\Delta v = 2\ m/s$, then $J=m\Delta v=95\times2 = 190\ kg\cdot m/s$.

Answer:

D. 190 kg·m/s