Advertisements
Advertisements
Question
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.
Solution
(a) Mass of bullet = 50g = `50/1000 = 1/20 kg`
Velocity = 500 m/s
∴ K.E. of bullet = `1/2 mv^2`
= `1/2 xx 1/20 xx 500 xx 500`
K.E. = 6250 J
(b) u = 500 m/s, v = 0 as bullet comes to rest
distance covered = 10 cm = `10/100 = 1/10 m`
v2 - u2 = 2aS
0 - 500 × 500 = `2a × 1/10`
∴ a = - 1250000 m/s-2
∴ Retardation = 1250000 m/s-2
But F = m × a
∴ Retarding force offered by target = `1/20 xx 1250000`
F = 62500 N
APPEARS IN
RELATED QUESTIONS
Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?
The energy of a flying kite is kinetic energy.
A ball of mass M is moving with a speed v. What is its kinetic energy?
When an arrow is shot from a bow, it has kinetic energy in it. Explain briefly from where does it get its kinetic energy?
If the speed of a body is halved, what will be the change in its kinetic energy?
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 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 :
The momentum of a bullet of mass 20 g fired from a gun is 10 kg.m/s. The kinetic energy of this bullet in kJ will be :
Find out the form of energy possessed by the following thing.
Water falls
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.
