Calculate the amount of work needed to stop a car of 500 kg, moving at

1.	Calculate the amount of work needed to stop a car of 500 kg, moving at a speed of 36 km/h.
Answer» Given Mass of car = 500 Kg Initial speed = 36 km/h = 10m/s (∵ 1 km/h = 5/18 m/s) Now Work done = Change in Kinetic Energy. = Final kinetic Energy – Initial Kinetic Energy. = \(\frac{m(v^2-u^2)}{2}\) = \(\frac{500(0-10^2)}{2}\) (Final velocity = 0, because the car is at rest). = 250 x -100 = -25000 J. The magnitude of work required is 25000 Joule.

Calculate the amount of work needed to stop a car of 500 kg, moving at a speed of 36 km/h.

Answer»

Given

Mass of car = 500 Kg

Initial speed = 36 km/h = 10m/s

(∵ 1 km/h = 5/18 m/s)

Now

Work done = Change in Kinetic Energy.

= Final kinetic Energy – Initial Kinetic Energy.

= \(\frac{m(v^2-u^2)}{2}\)
= \(\frac{500(0-10^2)}{2}\) (Final velocity = 0, because the car is at rest).
= 250 x -100 = -25000 J.

The magnitude of work required is 25000 Joule.