Finding braking force needed to stop a 1500kg car in 50m

[Apothem]

Homework Statement

"The constant force resisting the motion of a car of mass 1500kg is 980N. If, when traveling at 48kmhr^-1, the car is brought to rest in a distance 50m by applying the brakes, find the additional retarding force due to the brakes (assumed constant)

Homework Equations

SUVAT: v²=u²+2as, rearranged to a=(v²-u²)/2s

Newton's Second Law: F=ma

The Attempt at a Solution

I used suvat (s=50m , u=48kmhr^-1=13.3ms^-1 [3.S.F.] , v=0ms^-1 , a=a , t=t) to calculate the deceleration as 1.77ms^-2 [3.S.F.], I then used F=ma, and found the force to be 2655N, is this right?

 

[Tanya Sharma]

Homework Statement

"The constant force resisting the motion of a car of mass 1500kg is 980N. If, when traveling at 48kmhr^-1, the car is brought to rest in a distance 50m by applying the brakes, find the additional retarding force due to the brakes (assumed constant)

Homework Equations

SUVAT: v²=u²+2as, rearranged to a=(v²-u²)/2s

Newton's Second Law: F=ma

The Attempt at a Solution

I used suvat (s=50m , u=48kmhr^-1=13.3ms^-1 [3.S.F.] , v=0ms^-1 , a=a , t=t) to calculate the deceleration as 1.77ms^-2 [3.S.F.], I then used F=ma, and found the force to be 2655N, is this right?

2655N is the net retarding force.

There are two retarding forces acting on the car.You need to deduct the constant force of 980N from the net force to get the force due to brakes .