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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: Verify that -(-x) = x for (i) x = 11/5 (ii) x = -13/17

(i) We have x = ∴ -x = -(-x) = - = = x (verified) [∵ (-) x (-) = (+)] (ii) We have x = - ∴ -x = = [∵ (-) x (-) = (+)] -(-x) = = ...

4 years ago
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Answer to: A car is moving on a level road. If the driver turns off the engine of the car, the car’s speed decreases gradually and ultimately it comes to a stop.

The two forces acting on the car are force of friction and air resistance. Force of friction contributes more to slow down and stop the car.

4 years ago
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Answer to: A man throws a ball weighing 500 g vertically upwards with a speed of 10 m/s. (i) What will be its initial momentum? (ii) What would be its momentum at the highest point of its flight?

Mass of ball = 500 g = 0.5 kg Initial velocity = 10 m/s (i) Initial momentum = 0.5 x 10 = 5 kg.m/s (ii) Velocity at the highest point = 0 m/s...

4 years ago
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Answer to: What happens to the passengers travelling in a bus when the bus takes a sharp turn? Give reasons for your answer. (b) Why are road accidents at high speeds very much worse than road accidents at low speeds?

(a) When a bus takes a sharp turn, the passengers tend to fall sideways because of their inertia or their tendency to continue moving in a straight li...

4 years ago
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Answer to: What do you understand by the terms “balanced forces” and “unbalanced forces”? Explain with examples. (b) What type of forces - balanced or unbalanced - act on a rubber ball when we press it between our hands?

(a) If the resultant of all the forces acting on a body is zero, the forces are called balanced forces. These forces do not change the state of rest o...

4 years ago
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Answer to: Give one example each where: (a) a force moves a stationary body. (b) a force stops a moving body.

(a) Kicking a stationary football. (b) Applying brakes to a moving bicycle. (c) Pressing an accelerator to speed up a moving car. (d) A moving...

4 years ago
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Answer to: (a) Define the term ‘force’. (b) State the various effects of force.

(a) Force is an influence which tends to set a stationary body in motion or stop a moving body; or which tends to change the speed and direction of a ...

4 years ago
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Answer to: Define momentum of a body. On what factors does the momentum of a body depend? (b) Calculate the change in momentum of a body weighing 5 kg when its velocity decreases from 20 m/s to 0.20 m/s.

(a) Momentum is the physical quantity which is the measure of the quantity of motion of a moving body. It depends on mass and velocity of the body. ...

4 years ago
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Answer to: What is the momentum in kg.m/s of a 10 kg car travelling at (a) 5 m/s (b) 20 cm/s, and (c) 36 km/h?

Mass of car, m = 10 kg Momentum = m x v (a) Velocity, v = 5 m/s Momentum = 10 x 5 = 50 kg.m/s (b) Velocity, v = 20 cm/s = 0.2 m/s Momen...

4 years ago
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Answer to: Explain why, it is dangerous to jump out of a moving bus.

It is dangerous to jump out of a moving bus because the jumping man, who is moving with the high speed of the bus would tend to remain in state of mot...

4 years ago
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Answer to: When a tree is shaken, its fruits and leaves fall down. Why?

When a tree is shaken, the tree moves to and fro while the fruits and leaves remain in their state of rest on account of their inertia and thus fruits...

4 years ago
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Answer to: Give reason for the following: When a hanging carpet is beaten with a stick, the dust particles start coming out of it.

When a hanging carpet is beaten with a stick, the carpet moves to and fro with the force of the stick while the dust particles remain in their state o...

4 years ago
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Answer to: Explain why, a person travelling in a bus falls forward when the bus stops suddenly.

When a bus stops suddenly, its passengers tend to fall forward because due to their inertia, the passengers tend to remain in a state of motion even t...

4 years ago
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Answer to: Why do the passengers in a bus tend to fall backward when it starts suddenly?

When a bus starts suddenly, its passengers tend to fall backwards because due to their inertia, the passengers tend to remain in a state of rest even ...

4 years ago
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Answer to: On what factor does the inertia of a body depend? Which has more inertia, a cricket ball or a rubber ball of the same size?

Inertia of a body depends on its mass. A cricket ball has more inertia than a rubber ball of the same size because it has more mass than the rubber ba...

4 years ago
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