# Assume a car and truck are moving with the Impulse same speed of 15 m/s. 1) Calculate momentum of the car of mass 975 kg 2) Calculate momentum of the truck of mass 2675 kg 3) Determine the force =? Needed to stop each in 25 s.

Nov 10, 2015

$1.$

$14625 \text{kg.m/s}$

$2.$

$40125 \text{kg.m/s}$

$3$.

$\left(a\right)$

$- 585 \text{N}$

$\left(b\right)$

$- 1605 \text{N}$

#### Explanation:

$1.$

Momentum = mass x velocity

$\therefore {M}_{1} = 975 \times 15 = 14625 \text{kg.m/s}$

$2.$

$\therefore {M}_{2} = 2675 \times 15 = 40125 \text{kg.m/s}$

$3.$

The acceleration is the change in velocity/time.

$a = \frac{0 - 15}{25}$

Force = mass x acceleration.

So for the 1st truck:

${F}_{1} = 975 \times \left(- \frac{15}{25}\right) = - 585 \text{N}$

So for the 2nd truck:

${F}_{2} = 2675 \times \left(- \frac{15}{25}\right) = - 1605 \text{N}$

The minus sign means this is a braking force.