Скачать или смотреть Conceptual Questions | Chapter 3 | Dynamics 1 | 9th Physics New Book | National Book Foundation

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3.1 If the same engine is installed in a bus and car that applies a force of 3000N. What acceleration will this engine produce in a bus of mass 12,000kg and a car of mass 1200kg?
3.2 Mass of your school bag is 8kg. How much will it weigh (a) here on Earth and on (b) the surface of moon? [Take acceleration due to gravity for Earth as 𝒈_𝒆=𝟗.𝟖〖𝒎𝒔〗^(−𝟐) and for Moon as 𝒈_𝒎=𝟏.𝟔𝟐𝟓〖𝒎𝒔〗^(−𝟐).
3.3 A box weighs 400N on earth while 150N on an unknown planet. Find the gravitational field strength on that planet.
3.4 A golfer hits a ball mass 45g. If after the shot, the ball travels with a speed of 80m/s, what magnitude of momentum does the golfer imparted to ball?
3.5 What is difficult to stop if their brakes fail and are travelling from an inclined road:
(a) A car of mass 1200kg moving with a velocity of 8m/s in 5 seconds,
(b) A truck of mass 10,000kg moving with the same velocity in the same time?
3.6 Ahmad fired a bullet of mass 17g from his hunting gun, of mass 3kg. If the velocity of the bullet were 350m/s, what would be the recoil velocity of the air gun?
When a hanging carpet is beaten by stick. Dust flies off the carpet. It is mainly due to:
(a) Action force on carpet (b) Reaction force by carpet
(c) Inertia of dust (d) Rate of change of momentum of carpet
A bucket having some water is revolved in vertical circle. Water does not spill out, even the bucket is upside down, due to:
(a) weight of water (b) Centrifugal force on water
(c) Inertia of water (d) Action and reaction balance each other
The force which moves the car is:
(a) Force developed by engine (b) Force of friction between road and tyre
(c) Weight of car (d) Water split on the road
N〖kg〗^(-1) is equal to:
(a) ms^(-1) (b) ms^(-2) (c) kgms^(-1) (d) kgs^(-2)
An object of mass 1kg placed at earth’s surface experiences a force of:
(a) 1N (b) 9.8N (c) 100N (d) any value
Net force on the body falling in air with uniform velocity is equal to
(a) weight of the body (b) air resistance on the body
(c) difference of weight of body & air resistance on it (c) zero
When a motor cyclist hit a stationary car, he may fly off the motor cycle and driver in the car may get neck injury. Explain
In autumn, when you shake a branch, the leaves are detached. Why?
Why it is not safe to apply brakes only on the front wheel of a bicycle?
Deduce Newton’s first law of motion from Newton’s second law of motion.
Action and reaction are equal but opposite in direction. These forces always act in pair. Do they balance each other? Can bodies move under action – reaction pair?
A man slips on the oily floor, he wants to move out of this area. He is alone. He throws his bag to move out of this slippery area. Why is it so?
How would you use Newton’s 3rd law of motion and law of conservation of momentum to explain motion of rocket?
Why are cricket batter gloves padded with foam?
Where will your weight be greater, near earth or near moon? What about mass?
When Ronaldo kicks the ball, at the highest point of ball both Earth and ball attract each other with the same magnitude of force. Why then the ball moves towards Earth and not the Earth?
A body is holding a book of mass 2kg. How much force is he applying on the book? If he moves it up with acceleration of 3ms^(-2), how much should he apply total force on the book?
A girl of mass 30kg is running with velocity of 4ms^(-1). Find her momentum.
A 2kg steel ball is moving with speed of 15ms^(-1). It hits with bulk of sand and comes to rest in 0.2 second. Find force applied by sand bulk on the ball.
A 100 gram bullet is fired from 5kg gun. Muzzle velocity of bullet is 20ms^(-1). Find recoil velocity of the gun.
A robotic car of 15kg is moving with 25ms^(-1). Brakes are applied to stop it. Brakes apply constant force of 50N. How long does the car take to stop?