Question

A driver of a mass 1200kg car notices that the car slows down from 20 m/s to 15 m/s as it moves a distance of 130m along the level ground. find the magnitude of the force acting on the car.

Answer 1

v i = 20 m/s

v f = 15 m/s

m = 1200kg

d = 130m

f = v/d

f= 1/2m Vi^2 - 1/2m Vf^2 / d

f= (1/2 x 1200) 20^2 - (1/2 x 1200)15^2 / 130 = .81kn

Answer 2

Answer:

f=804N

Explanation:

concept- use 3rd equation of motion v^2-u^2=2as then find acceleration from it then use f=ma

given - v, final velocity= 15m/s

u, initial velocity= 20m/s

m= 1200kg

s= 130m

find = force

explanation=

v^2-u^2=2as

(15)^2- (20)^2= 2*a* 130

225-400/260= a

a=.67m/s^2

f= ma

f= 1200*.67

f= 804 N

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