Laws of Motion Physics - Laws of Motion

A hockey player is moving northward and suddenly turns westward with the same speed to avoid an opponent. The force that acts on the player is:

1. Frictional force along westward.
2. Muscle force along southward.
3. Frictional force along south-west.
4. Muscle force along south-west.

In the previous problem (5.3), the magnitude of the momentum transferred during the hit is:

1. Zero
2. 0.75kg m s^–1
3. 1.5kg m s^–1
4. 14kg m s^–1

Conservation of momentum in a collision between particles can be understood from:

1. Conservation of energy.
2. Newton’s first law only.
3. Newton’s second law only.
4. Both Newton’s second and third law.

In the co-efficient of friction between the floor and the body B is 0.1. The co-efficient of friction between the bodies B and A is 0.2. A force F is applied as shown on B. The mass of A is m/ 2 and of B is m. Which of the following statements are true?

1. The bodies will move together if F = 0.25mg.
2. The body A will slip with respect to B if F = 0.5mg.
3. The bodies will move together if F = 0.5mg.
4. The bodies will be at rest if F = 0.1mg.
5. The maximum value of F for which the two bodies will move together is 0.45mg.

A body of mass 2kg travels according to the law x(t) = pt + qt² rt³ where p = 3m s^-1, q = 4m s^-2 and r = 5m s^-3. The force acting on the body at t = 2 seconds is.

1. 136N
2. 134N
3. 158N
4. 68N

Why does a child feel more pain when she falls down on a hard cement floor, than when she falls on the soft muddy ground in the garden?

Why are mountain roads generally made winding upwards rather than going straight up?

Why are porcelain objects wrapped in paper or straw before packing for transportation?

In the above given problem if the lower thread is pulled with a jerk, what happens?

A person driving a car suddenly applies the brakes on seeing a child on the road ahead. If he is not wearing seat belt, he falls forward and hits his head against the steering wheel. Why?

A mass of 2kg is suspended with thread AB Thread CD of the same type is attached to the other end of 2kg mass. Lower thread is pulled gradually, harder and harder in the downward directon so as to apply force on AB. Which of the threads will break and why?

A woman throws an object of mass 500g with a speed of 25m s¹.
What is the impulse imparted to the object?

A person of mass 50kg stands on a weighing scale on a lift. If the lift is descending with a downward acceleration of 9m s^–2, what would be the reading of the weighing scale? (g = 10m s^–2)

A block placed on a rough horizontal surface is pulled by a horizontal force F. Let f be the force applied by the rough surface on the block. Plot a graph of f versus F.

A woman throws an object of mass 500g with a speed of 25m s¹.

If the object hits a wall and rebounds with half the original speed, what is the change in momentum of the object?

A cricket bowler releases the ball in two different ways.

1. Giving it only horizontal velocity, and
2. Giving it horizontal velocity and a small downward velocity. The speed v_s at the time of release is the same. Both are released at a height H from the ground. Which one will have greater speed when the ball hits the ground? Neglect air resistance.

A person in an elevator accelerating upwards with an acceleration of 2m s^–2, tosses a coin vertically upwards with a speed of 20m s¹. After how much time will the coin fall back into his hand? (g = 10m s^–2)

The position time graph of a body of mass 2kg is as given in What is the impulse on the body at t = 0 s and t = 4s.

A helicopter of mass 2000kg rises with a vertical acceleration of 15m s^–2. The total mass of the crew and passengers is 500kg. Give the magnitude and direction of the (g = 10m s^–2)

1. Force on the floor of the helicopter by the crew and passengers.
2. Action of the rotor of the helicopter on the surrounding air.
3. Force on the helicopter due to the surrounding air.

A 100kg gun fires a ball of 1kg horizontally from a cliff of height 500m. It falls on the ground at a distance of 400m from the bottom of the cliff. Find the recoil velocity of the gun. (acceleration due to gravity = 10m s^–2)