Home / Class 9 Science / Chapter 11 Work Energy and Power MCQ Test 1 Science Class 9 Science
Online Test of Chapter 11 Work Energy and Power 1 Science| Class 9th
1. A body is acted upon by a force 25 N acquires of 2.5 ms^{-2} and covers a distance of the force. If the body starts from rest, the Kinetic energy acquired by it is?
(i) 75 J
(ii) 25 J
(iii) 250 J
(iv) 100 J
2. A freely falling body during its fall will have
(i) Kinetic energy
(ii) Potential energy
(iii) Sound energy
(iv) Both kinetic energy and potential energy
3. A boy climbs on to a wall that is 3.4 m high and gains 2250 J of potential energy. What is the mass of the boy? Take g = 9.8 m/sec^{2
}(i) 70 kg
(ii) 50 kg
(iii) 67.5 kg
(iv) 62.5 kg
4. A body of mass 4 kg has a momentum of 25 kg m/s, its K.E. is:
(i) 70.66 J
(ii) 78.12 J
(iii) 100 J
(iv) 25.5 J
5. What happens to K.E. of a body when 3/4 th of mass is removed and its velocity is doubled?
(i) becomes 4 times
(ii) no change
(iii) becomes 1/2 times
(iv) becomes 1/4 times
6. Elastic potential energy of a body can be achieved by
(i) setting it into motion
(ii) raising the body to a height
(iii) using an elastic band to tie the body
(iv) compressing or stretching the body
7. If the velocity of a moving car is halved, its kinetic energy would
(i) Double
(ii) Become Half
(iii) Become one fourth
(iv) Remain same
8. A fish with weight 35 kg dives and hits the ground (zero height) with kinetic energy equal to 3500J. Find the height through which fish dived. Take g = 10 m/s^{2
}(i) 1 km
(ii) 100 m
(iii) 10 m
(iv) 20 m
9. Which of the following is not an example of potential energy?
(i) A compressed spring
(ii) Water stored in the reservoir of dam
(iii) A stretched rubber band
(iv) A moving car
10. How fast should a person with mass 50kg walk so that his kinetic energy is 625 J ?
(i) 15 km/s
(ii) 0.5 m/s
(iii) 5 m/s
(iv) 5 Km/s
Work and Energy Class 9 MCQ - 1
Time limit: 0
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Question 1 of 10
1. Question
A body is acted upon by a force 25 N acquires of 2.5 ms^{-2} and covers a distance of the force. If the body starts from rest, the Kinetic energy acquired by it is?
Correct
Incorrect
Question 2 of 10
2. Question
A freely falling body during its fall will have
Correct
Solution: Object Falling from Rest. As an object falls from rest, its gravitational potential energy is converted to kinetic energy. Conservation of energy as a tool permits the calculation of the velocity just before it hits the surface. K.E. = J, which is of course equal to its initial potential energy.
Incorrect
Solution: Object Falling from Rest. As an object falls from rest, its gravitational potential energy is converted to kinetic energy. Conservation of energy as a tool permits the calculation of the velocity just before it hits the surface. K.E. = J, which is of course equal to its initial potential energy.
Question 3 of 10
3. Question
A boy climbs on to a wall that is 3.4 m high and gains 2250 J of potential energy. What is the mass of the boy? Take g = 9.8 m/Sec^{2}
Correct
P.E. = mgh
Therefore m = P.E. / gh =( 2250/ (9.8× 3.4))
= (2250/33.32) kg = 67.5 kg
Incorrect
P.E. = mgh
Therefore m = P.E. / gh =( 2250/ (9.8× 3.4))
= (2250/33.32) kg = 67.5 kg
Question 4 of 10
4. Question
A body of mass 4 kg has a momentum of 25 kg m/s, its K.E. is:
Correct
The correct answer is B asMomentum = mass × velocity
4 = 25 × v
V = 4/25
V = 6.25
To find the kinetic energy ,
KE = 1/2 mv^{2
}= 1/2 × 25 ×6.25×6.25
= 78.12 J
Incorrect
The correct answer is B asMomentum = mass × velocity
4 = 25 × v
V = 4/25
V = 6.25
To find the kinetic energy ,
KE = 1/2 mv^{2
}= 1/2 × 25 ×6.25×6.25
= 78.12 J
Question 5 of 10
5. Question
What happens to K.E. of a body when 3/4 th of mass is removed and its velocity is doubled?
Correct
The correct answer is B as
let the mass=m
then, m-3/4m=m/4
and velocity=2v
kinetic energy=1/2×mv^{2}
=1/2×m/4×(2v^{2})
=1/2×m/4×4v^{2}
=1/2mv^{2}
Incorrect
The correct answer is B as
let the mass=m
then, m-3/4m=m/4
and velocity=2v
kinetic energy=1/2×mv^{2}
=1/2×m/4×(2v^{2})
=1/2×m/4×4v^{2}
=1/2mv^{2}
Question 6 of 10
6. Question
Elastic potential energy of a body can be achieved by
Correct
Incorrect
Question 7 of 10
7. Question
If the velocity of a moving car is halved, its kinetic energy would
Correct
Kinetic Energy = (^{1}/_{2}) mv^{2}.
If the velocity of a body is halved, its kinetic energy becomes one fourth as kinetic energy is directly proportional to velocity squared.
Incorrect
Question 8 of 10
8. Question
A fish with weight 35 kg dives and hits the ground (zero height) with kinetic energy equal to 3500J. Find the height through which fish dived. Take g = 10 m/s^{2}
Correct
Using the consersative law of
Energy formula
Change in potential energy =kinetic energy
M .g. h = 3500 J
35 . 10.h = 3500
h=10m
Incorrect
Using the consersative law of
Energy formula
Change in potential energy =kinetic energy
M .g. h = 3500 J
35 . 10.h = 3500
h=10m
Question 9 of 10
9. Question
Which of the following is not an example of potential energy?
Correct
The correct option is D.
A moving car is an example of kinetic energy whereas water stored in a dam, compressed spring and stretched rubber band are examples of potential energy.
Incorrect
The correct option is D.
A moving car is an example of kinetic energy whereas water stored in a dam, compressed spring and stretched rubber band are examples of potential energy.
Question 10 of 10
10. Question
How fast should a person with mass 50kg walk so that his kinetic energy is 625 J ?
Correct
K.E = 0.5mv²
v = √(2K.E / m)
= √(2 × 625 Joule / 50 kg)
= √(625 Joule / 25 kg)
= 5 m/s…
Incorrect
K.E = 0.5mv²
v = √(2K.E / m)
= √(2 × 625 Joule / 50 kg)
= √(625 Joule / 25 kg)
= 5 m/s…