Advertisements
Advertisements
Question
How fast should a man of 50 kg run so that his kinetic energy be 625 J?
Advertisements
Solution
We have to find the speed of the running man. We have,
Mass of the man (m) = 50 kg
Kinetic energy of the man (K.E) = 325 J
So, we use the expression of kinetic energy to find the unknown quantity as,
`K.E = 1/2 mv^2`
Where,
KE - Kinetic Energy
m - Mass
v - Speed
So,
`v = sqrt((2(K.E))/((m))`
Therefore ,
`v = sqrt((2(625))/((50))` m/s
= `sqrt(25)` m/s
= 5 m/s
So , the man should be running with a speed of 5 m/s .
APPEARS IN
RELATED QUESTIONS
Write an expression for the kinetic energy of an object.
Give reasons for the following A horse and a dog are running with the same speed. Which one of them has more kinetic energy than the other.
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?
A body falls freely under gravity from rest. Name the kind of energy it will possess on reaching the ground.
Write an expression for the kinetic energy of a body of mass m moving with a velocity v.
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.
Derive the formula for the kinetic energy of an object of mass m, moving with velocity v.
If the mass as well as the velocity of a body is doubled then the kinetic energy of the body ______ the initial kinetic energy.
A ball of mass 0.5 kg slows down from a speed of 10 m s−1 to that of 6 m s−1. Calculate the change in the kinetic energy of the ball.
