Advertisements
Advertisements
प्रश्न
How fast should a man of 50 kg run so that his kinetic energy be 625 J?
उत्तर
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
संबंधित प्रश्न
An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.
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?
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.
A bullet of mass 50 g is moving with a velocity of 500 m s-1. It penetrated 10 cm into a still target and comes to rest. Calculate:
- the kinetic energy possessed by the bullet, and
- the average retarding force offered by the target.
A body of mass 60 kg has the momentum 3000 kg m s-1. Calculate:
- the kinetic energy.
- the speed of the body.
A body is thrown vertically upwards. Its velocity keeps on decreasing. What happens to its kinetic energy as its velocity becomes zero?
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)
Explain the types of mechanical energy.
When a bell fixed on a cycle rings, then the energy conversion that takes place is ______.
Find the kinetic energy of a body of mass 5 kg moving with a uniform velocity of 10 m s-1.
