Advertisements
Advertisements
Question
Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?
Advertisements
Solution
Here, the mass of the car, m = 1500 kg
The initial velocity of the car, u = 60 km h-1
= `(60 xx 1000 m)/(60 xx 60 s)`
= `50/3 ms^-1`
The initial kinetic energy of the car,
`K.E_i = 1/2 "mu"^2`
= `1/2 (1500 kg) (50/3 ms^-1)^2`
= 208333.3 J
Final kinetic energy of the car,
`K.E_f = 1/2 mv^2`
= 0
Change in kinetic energy of the car
= K.Ef - K.Ei
= - 208333.3 J
The minus sign indicates the work is being done against the moving car.
APPEARS IN
RELATED QUESTIONS
An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest?
The energy of a flying kite is kinetic energy.
When a boy doubles his speed, his kinetic energy becomes
Two toy-cars A and Bof masses 200 g and 500 g respectively are moving with the same speed. Which of the two has greater kinetic energy?
How much work is needed to be done on a ball of mass 50 g to give it a momentum of 5 kg cm s-1?
What is the kinetic energy of a body of mass 1 kg moving with a speed of 2 m/s?
On a level road, a scooterist applies brakes to slow down from a speed of 10 m/s to 5 m/s. If the mass of the scooterist and the scooter be 150 kg, calculate the work done by the brakes. (Neglect air resistance and friction)
The energy possessed by a cricket ball bowled by a player is ______.
A body starts from rest and is acted on by a constant force. The ratio of kinetic energy gained by it in the first five seconds to that gained in the next five-second is:
If the mass as well as the velocity of a body is doubled then the kinetic energy of the body ______ the initial kinetic energy.
