Advertisements
Advertisements
Question
A car is moving with a speed of 15 km h-1 and another identical car is moving with a speed of 30 km h-1. Compare their kinetic energy.
Advertisements
Solution
Two identical cars mean, they have equal mass
K.E = 1/2 mv2
Let m be the mass of each car
Kinetic energy of car A = `1/2` m × `(15)^2` = `225/2` m
= 112.5 m J
Kinetic energy of car B = 1/2 M (30)2
=450 M J
`(K.E. of A) /(K.E. of B)` = `(225 m )/(2 × 450 m )` = `1/4` = 1 : 4
K.E. of car B is 4 times K.E. of car A.
APPEARS IN
RELATED QUESTIONS
Certain force acting on a 20 kg mass changes its velocity from 5 m s-1 to 2 m s-1. Calculate the work done by the force.
Name the unit of physical quantity obtained by the formula `(2K)/v^2` Where K: kinetic energy, v: linear velocity
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?
By how much will the kinetic energy of a body increase if its speed is doubled?
A ball of mass 200 g falls from a height of 5 metres. What is its kinetic energy when it just reaches the ground? (g = 9.8 m/s2)
Find the momentum of a body of mass 100 g having a kinetic energy of 20 J.
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)
When a ball is thrown inside a moving bus, does its kinetic energy depend on the speed of the bus? Explain.
Explain the difference between potential energy and kinetic energy.
Explain the types of mechanical energy.
