# Grantham PHY220 Week 2 Assignment Problem 5

### If a 1500 kg car stopped from an in 5.6 seconds with an applied force of 5000 N, how fast was it initially traveling?

Solution:

There is a negative acceleration since the car decelerates.

$F=ma$

$a=\frac{F}{m}=\frac{5000\:N}{1500\:kg}=-3.33\:m/s^2$

$v=v_0+at$

$v_0=v-at$

$v_0=0-\left(-3.33\:m/s^2\right)\left(5.6\:s\right)$

$v_0=18.6\:m/s$

The car was initially traveling at $18.6\:m/s$.