Advertisements
Advertisements
प्रश्न
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)
Advertisements
उत्तर
Mass of the ball, (m) = 0.2 kg
Height from which the ball is dropped, (h) = 5 m
Initial velocity of the ball, (u) = 0 m/s
Acceleration due to gravity, (g) = 9.8 m/s2
Let the final velocity of the ball when it just reaches the ground be (v)
We will use the third equation of motion to find the velocity of the ball when it just reaches the ground,
v2 = u2 + 2as
So,
v2 = 0 + 2(9.8)(5)
⇒ v2 = 98
Now we can find the kinetic energy as,
`K.E = 1/2 mv^2`
Therefore,
K.E = (1/2)(0.2)(98)
⇒ K.E = 9.8 J
So, the kinetic energy of the moving object is 9.8 J.
APPEARS IN
संबंधित प्रश्न
The kinetic energy of an object of mass m moving with a velocity of 5 m s−1 is 25 J. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?
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?
Write the expression for the kinetic energy of a body explaining the meaning of the symbols used.
If the speed of a car is halved, how does its kinetic energy change?
A body of mass 10 kg is moving with a velocity 20 m s-1. If the mass of the body is doubled and its velocity is halved, find:
- the initial kinetic energy, and
- the final kinetic energy.
A body of mass 60 kg has the momentum 3000 kg m s-1. Calculate:
- the kinetic energy.
- the speed of the body.
If the speed of a body is halved, what will be the change in its kinetic energy?
Find the momentum of a body of mass 100 g having a kinetic energy of 20 J.
The energy possessed by a cricket ball bowled by a player is ______.
