Question

{100 POINTS + Brainliest} Driving home from school one day, you spot a ball rolling out into the street (see the figure (Figure 1)). You brake for 1.00 s , slowing your 920-kg car from 16.0 m/s to 9.50 m/s.

What was the magnitude of the average force exerted on your car during braking?
What was the direction of the average force exerted on your car during braking?
How far did you travel while braking? in meters

Answer 1

Explanation:

According to the question ,

• mass = 920kg
• time = 1s
• Initial velocity = 16m/s
• Final velocity = 9.5m/s

And we need to find out ,

• Average force

As we know that Force is the rate of change of momentum ,

$\sf\red{\longrightarrow}$ F = ∆p/t

$\sf\red{\longrightarrow}$ F = mv - mu/t

$\sf\red{\longrightarrow}$ F = m(v - u)/t

$\sf\red{\longrightarrow}$ F = 920(9.5-16)/1 N

$\sf\red{\longrightarrow}$ F = 920 * -6.5 N

$\sf\red{\longrightarrow}$ Force = -5980N

• Direction of the force ?

The direction of the force will be opposite to the direction of velocity of the car .

• Distance travelled while breaking ?

Using the 3rd equation of motion , we have ,

$\sf\red{\longrightarrow}$ 2as = v² - u²

$\sf\red{\longrightarrow}$ 2 (v-u)/t *s =(v+u)(v-u)

$\sf\red{\longrightarrow}$ 2(t)(s) = v + u

$\sf\red{\longrightarrow}$ 2 * 1 * s = 16 + 9.5

$\sf\red{\longrightarrow}$ s = 25.5/2 m

$\sf\red{\longrightarrow}$ s = 12.75 m