- #1

Barclay

- 208

- 1

## Homework Statement

Seasons greetings everyone. Merry Christmas and happy new year to all.

The brakes of a car can provide 6.5kN of force and the mass of the car is 1000kg. What is the stopping distance for car A traveling at 30km/h and car B traveling at 45km/h.

The answer in the book is A = 5.3m B = 12m

I did not get these answers and I can't figure out where I made the error. Please advise.

## Homework Equations

f=ma

a=rate of change of speed = (v-u)/t

speed = distance / time = d/t

3. The Attempt at a Solution

3. The Attempt at a Solution

For both cars f=ma

a=(6.5 x 10

^{3})/1000 = 6.5m/s

^{2}

Car A: 30km/h = 8.3m/s

^{2}

Car B : 45km/h = 12m/s

^{2}Acceleration for car A: a=(v-u)/t

t=(v-u)/a t = (8.3-0)/6.5

t = 1.27s time to stop the car A

Acceleration for car B: a=(v-u)/t

t=(v-u)/a = (12-0)/6.5

t= 1.84s to stop the car Bspeed=d/t so for car A distance = speed x time = 8.3 x 1.27 = 10.5m

speed=d/t so for car B distance = speed x time = 12 x 1.84 = 22m

#### Attachments

Last edited by a moderator: