Advertisements
Advertisements
प्रश्न
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.
उत्तर
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
संबंधित प्रश्न
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?
If the speed of a car is halved, how does its kinetic energy change?
A cannon ball of mass 500 g is fired with a speed of 15 m s-1. Find:
- its kinetic energy.
- its momentum.
By how much will the kinetic energy of a body increase if its speed is doubled?
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)
A man drops a 10 kg rock from the top of a 5 m ladder. What is its speed just before it hits the ground? What is its kinetic energy when it reaches the ground? (g = 10 m/s2)
What do you understand by the kinetic energy of a body?
A horse and a dog are running with the same speed. If the weight of the horse is ten times that of the dog, What is the ration of their kinetic energies?
The kinetic energy of a body of mass 4 kg and momentum 6 Ns will be
