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Mayank1444
@mayank1444
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Joined: Oct 11, 2021
Last seen: Nov 14, 2021
Topics: 0 / Replies: 2157
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Answer to: A boy weighing 50 kg climbs up a vertical height of 100m. Calculate the amount of work done by him. How much potential energy does he gain?

Height, h = 100m Acceleration due to gravity, g = 9.8 m/s2 Work done by the boy, W = mgh = 49kJ Potential energy gained = work done by the boy...

4 years ago
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Answer to: A body of mass 100kg is lifted up by 10m. Find: (a) the amount of work done (b) potential energy of the body at that height

Height, h = 10 m Acceleration due to gravity, g = 10m/s2 (a) Work done, W = mgh = 10kJ (b) Potential energy of the body = work done = 10 kJ

4 years ago
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Answer to: Calculate the work done by the brakes of a car of mass 1000 kg when its speed is reduced from 20 m/s to 10 m/s.

Mass of car = 1000 kg Initial velocity, u = 20 m/s Final velocity, v = 10 m/s Retardation = a Distance covered = s Using third equation...

4 years ago
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Answer to: A man drops a 10 kg rock from the top of a 5m ladder. What is its speed just before it hits the ground? What is its kinetic energy when it reaches the ground?

Mass of rock = 10 kg Height of ladder, h = 5m Initial velocity of rock, u = 0 Final velocity, v g = 10 m/s2 Using third equation of moti...

4 years ago
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Answer to: 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 150kg, calculate the work done by the brakes.

Mass of scooter + scooterist = 150 kg Initial velocity, u = 10 m/s Final velocity, v = 5 m/s Retardation = a Distance travelled = s Usi...

4 years ago
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Answer to: A body of 2 kg falls from rest. What will be its kinetic energy during the fall at the end of 2s?

Mass of body = 2 kg Initial velocity, u = 0 Time taken, t = 2 s Acceleration due to gravity, g = 10 m/s2 Final velocity, v = ? Using the...

4 years ago
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Answer to: Find the momentum of a body of mass 100g having a kinetic energy of 20J.

KE = 20 J Mass = 100g = 0.1 kg KE = mv2 v2 = 400 v = 20 m/s Momentum = mv = 2 kg.m/s

4 years ago
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Answer to: A ball of mass 200g falls from a height of 5 meters. What is its kinetic energy when it just reaches the ground?

Mass = 200 g = 0.2kg Height = 5m Initial velocity, u = 0 Acceleration due to gravity, g = 9.8 m/s2 Final velocity, v Using third equatio...

4 years ago
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Answer to: Give one example each in which a force does (a) positive work (b) negative work (c) zero work

(a) Positive work: When a ball is thrown upwards, work done by the force is positive work. (b) Negative work: Work done by the gravitational force ...

4 years ago
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Answer to: How does the kinetic energy of a moving body depend on its (a) speed (b) mass

(a) Kinetic energy is directly proportional to the speed. (b) Kinetic energy is directly proportional to the mass.

4 years ago
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Answer to: Write the formula for work done on a body when the body moves at an angle to the direction of force. Give the meaning of each symbol used.

W = F cosθ s Where, W is the work done F is the force applied s is the distance travelled by the body θ is the angle between the direction...

4 years ago
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Answer to: A boy throws a rubber ball vertically upwards. What type of work, positive or negative is done: (a) by the force applied by the boy? (b) by the gravitational force of earth?

(a) The force applied by the boy is a positive work as it is in the direction of motion of the body. (b) The work done by the gravitational force o...

4 years ago
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Answer to: Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.

Yes, it is possible that a force is acting on a body and still the work done is zero. When a man is pushing a wall, work done is zero as there is n...

4 years ago
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Answer to: What are the quantities on which the amount of work done depends? How are they related to work?

Following are the quantities on which the amount of work done depends: (a) magnitude of the force (b) distance through which the body moves Forc...

4 years ago
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Answer to: Work is measured as a product of ………. and ……….. (b) The work done on a body moving in a circular path is

(a) Force, distance (b) Zero (c) Newton, meter, force (d) Energy, kinetic energy (e) Mechanical

4 years ago
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Answer to: What kind of energy is possessed by the following: (a) a stone kept on roof-top (b) a running car (c) water stored in the reservoir of a dam

(a) Potential energy (b) Kinetic energy (c) Potential energy (d) Potential energy (e) Potential energy

4 years ago
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Answer to: What happens to the potential energy of a body when its height is doubled?

Potential energy is directly proportional to the height. Therefore, when the height is doubled, potential energy also gets doubled.

4 years ago
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Answer to: A load of 100 kg is pulled up by 5 m. Calculate the work done.

Mass = 100 kg Height = 5 m g = 9.8 m/s2 PE = mgh = 4900 J Work done = potential energy

4 years ago
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