Advertisements
Advertisements
प्रश्न
A cyclist doubles his speed. How will his kinetic energy change: increase, decrease or remain same?
Advertisements
उत्तर
As Kinetic energy K.E. = 1/2 Mv2
Since speed is doubled, its square will become 4 times
∴ K.E. increases i.e. become 4 times.
Or
K.E j = Mv2
When speed is doubled New speed v1 = (2 v)
New K.`E_2`= `1/2`M`V_1^2`
∴ New K.`E_2`= `1/2` M (2v`)^2`
K.`E_2`=`1/2` M 4`V^2`=4`[ 1/2M V^2]`
(¡¡) ÷ (¡)
=`(KE_2)/(KE_1)` =`(4[1/2MV^2])/([1/2 M V^2])`=`4/1`
=`(KE_2)/(KE_1)`
New K.`E._2`=4 Times K.`E_1`
APPEARS IN
संबंधित प्रश्न
When a boy doubles his speed, his kinetic energy becomes
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 truck weighing 1000 kgf changes its speed from 36 km h-1 to 72 km h-1 in 2 minutes. Calculate:
- the work done by the engine and
- its power (g = 10 m s-2)
A body is thrown vertically upwards. Its velocity keeps on decreasing. What happens to its kinetic energy as its velocity becomes zero?
Write an expression for the kinetic energy of a body of mass m moving with a velocity v.
How fast should a man of 50 kg run so that his kinetic energy be 625 J?
What do you understand by the kinetic energy of a body?
A car is accelerated on a levelled road and attains a speed of 4 times its initial speed. In this process, the kinetic energy of the car :
Find out the form of energy possessed by the following thing.
A rolling ball
