A 2.1 times 103 - kg car starts from rest at the top of a 5.0 - m - long driveway that is inclined at 20 deg with the horizontal. If an average friction force of 4.0 times 103 N impedes the motion, find the speed of the car at the bottom of the driveway.

speed of the car at the bottom of the driveway is 3.8 m/s

Explanation:

given data

mass = 2.1 * 10³ kg

distance = 5 m

angle = 20 degree

average friction force = 4 * 10³ N

to find out

find the speed of the car at the bottom of the driveway

solution

we find acceleration a by force equation that is

force = mg*sin20 - friction force

ma = mg*sin20 - friction force

put here value

2100a = 2100 (9.8) * sin20 - 4000

a = 1.447 m/s²

so from motion of equation

v²-u² = 2as

here u is 0 by initial speed and v is velocity and a is acceleration and s is distance

v²-0 = 2 (1.447) (5)

v = 3.8

speed of the car at the bottom of the driveway is 3.8 m/s