A car is strapped to a rocket (combined mass = 661 kg), and its kinetic energy is 66,120 J.

At this time, the rocket runs out of fuel and turns off, and the car deploys a parachute to slow down, and the parachute performs 36,733 J of work on the car.

What is the final speed of the car after this work is performed?

9.4 m/s

Explanation:

The work-energy theorem states that the work done on an object is equal to the change in kinetic energy of the object.

So we can write:

where in this problem:

W = -36.733 J is the work performed on the car (negative because its direction is opposite to the motion of the car)

is the initial kinetic energy of the car

is the final kinetic energy

Solving for Kf,

The kinetic energy of the car can be also written as

where:

m = 661 kg is the mass of the car

v is its final speed

Solving, we find

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