How much work must be done in the car to slow it from 100km/h to 50km/h

Work done=376.22MJ

Explanation:

The following problem can be solved using work-energy theorem

Work-Energy Theorem:

For system of particles

  ∑Wext+ ∑Wint= ΔK

where ∑Wext is the work done by the external forces on the system and ∑Wint is the work done by internal forces on the system. Newton's third law of motion gives you that ∑Fint=0, but the work done by internal forces may or may not be 0.

now coming back to our problem

1=

2=

Let us assume that average mass of the car(m) is and ∑Wint=0J

Therefore, Work done(W)=ΔK

=K₂-K₁

=

=

=376.22KJ

i'm thinking more like energy