MEDIUM
9th CBSE
IMPORTANT
Earn 100

The work done by the heart is 1 J per beat. Find the power of the heart if it beats 72 times per minute.

Important Questions on Work and Energy

MEDIUM
9th CBSE
IMPORTANT
Physics For Class 9>Chapter 4 - Work and Energy>Exercise>Q 11
Two girls A and B each of weight 400 N, climb up a tree of a height of 8 m. Girl A takes 20 s while B takes 50 s to accomplish this task. What is the power expended by each girl?
EASY
9th CBSE
IMPORTANT
Physics For Class 9>Chapter 4 - Work and Energy>Exercise>Q 12
A certain household consumes 650 units of electricity in a month. How much is this electricity in joule?
MEDIUM
9th CBSE
IMPORTANT
Physics For Class 9>Chapter 4 - Work and Energy>Exercise>Q 13
Five electric fans of 120 watt each are used for 4 hours. Calculate the electrical energy consumed in kilowatt hours.
MEDIUM
9th CBSE
IMPORTANT
Physics For Class 9>Chapter 4 - Work and Energy>Exercise>Q 1
The following data was obtained for a body of mass 1 kg dropped from a height of 5 meters: Distances above ground and corresponding velocities are mentioned as below:
5 m, 0 m/s
3.2 m, 6 m/s
0 m, 10 m/s
Show by calculations that the above data verifies the law of conservation of energy (Neglect air resistance). (g = 10 m/s2)
MEDIUM
9th CBSE
IMPORTANT
Physics For Class 9>Chapter 4 - Work and Energy>Exercise>Q 2
A ball falls to the ground as shown below:
Question Image
 What is the kinetic energy of ball when it hits the ground?
 
MEDIUM
9th CBSE
IMPORTANT
Physics For Class 9>Chapter 4 - Work and Energy>Exercise>Q 2
A ball falls to the ground as shown below:
Question Image
 What is the potential energy of ball at B? State the law which is used for answering the question.