# Kinetic Energy Problem

A moving object generally said to have kinetic energy. Many interesting things are there with kinetic energy, but kinetic energy can be easily explained with problems. Want to dig more for kinetic energy problems??!! You are just one step away. Click here to know more about kinetic energy problem.

# Kinetic Energy Problem

### Problem 1

Which car has more kinetic energy, the regular car or the race car? Answer: The race car has more kinetic energy because it has a higher velocity.

### Problem 2

Which of the following will hurt more, getting hit by 10 foot wave or by 1 foot wave? Answer: The bigger foot wave hurt more since it has more mass even though they travel at the same speed.

### Problem 3

The bird has a mass of 3 kg. It is flying at a speed of 10 m/s. Find its kinetic energy. Answer: KE = ½ mv^2 KE = ½ (3 kg) (10 m/s)^2 KE = 150 J

### Problem 4

Raja has a mass of 40 kg and running at a velocity of 2 m/s. How much kinetic energy does he have? Express them with correct units. Answer: KE = ½ mv^2 KE = ½ (40 kg) (2 m/s)^2 KE = ½ 40 kg x 4 (m/s)^2 KE = 160/2 kg.m^2/s^2 KE = 80 J

### Problem 5

A herder is herding his sheep into the kraal. A mother sheep and its lamb are both running at 2,7 m·s−1 towards the kraal. The sheep has a mass of 80 kg and the lamb has a mass of 25 kg. Calculate the kinetic energy for each of the sheep and the lamb

Solution

Given data:

• Velocity or speed of mother sheep and lamp, v =2.7 m·s−1
• Mass of the mother sheep = 80 kg
• Mass of the lamb = 25 kg

To find

• Kinetic energy of mother sheep
• Kinetic energy of lamb

Formula

• Kinetic energy of the object = ½*mv^2

Calculation

Kinetic energy of mother sheep

K.E

=1/2*(80)*(2.7)^2

= 2916 Joules

kinetic energy of lamb

K.E

=1/2*(25)*(2.7)^2

= 1913 Joules

### Note

Even though the sheep and the lamb are running at the same velocity, due to their different masses, they have different amounts of kinetic energy. The sheep has more than the lamb because it has a higher mass.

### Problem 6

A rocket of mass 1.5x104 kg accelerates at 220m/s2  for 29s from an initial speed of 5200m/s.

(a) How fast will be rocket be travelling after the 29s?

(b) How much Kinetic Energy has the rocket gained?

Solution:

Given data:

t = time = 29s

a = acceleration = 220m/s2

v = final speed = ?

u = initial speed = 5200m/s

Formula

(a) a=(v-u)/t

v – u = at

v = u + at

v = u + at

Calculation

(a) v = u + at

v = 5200 + (220 x 29)

= 5200 + 6380

so

v = 11580m/s

(b) Now KE=½(mv^2)

Initial Kinetic Energy =0.5 x (1.5x104) x (5200)^2

=2.028 x 1011J

Final Kinetic Energy =0.5 x (1.5x104) x (11580)^2

=1.006 x 1012J

Kinetic Energy gained = Final Kinetic Energy- Initial Kinetic Energy

=1.006 x 1012J - 2.028 x 1011J

= 8.032 x 1011J