Advertisements
Advertisements
प्रश्न
A person drops a coin. Describe the path of the coin as seen by the person if he is in
- a car moving at constant velocity and
- in a free falling elevator.
Advertisements
उत्तर
When the person drops the coin, the path of the coin as seen by the person is:
(a)
- When a person drops a coin inside a car moving at constant velocity, the coin appears to fall straight down from the person’s point of view.
- This is because both the person and the coin are moving forward with the same velocity as the car.
- There is no additional force acting on the coin in the horizontal direction, so the coin retains its forward motion and lands directly below the point from which it was dropped.
- This situation reflects the principle of relative motion and supports Newton’s first law an object in motion continues in motion unless acted upon by an external force.
(b)
- In a free falling elevator, both the person and the coin are accelerating downward at the same rate due to gravity.
- When the person drops the coin, from their point of view, it appears to hover, float in the air, or fall very slowly.
- The person and the coin are both in free fall together, so there is no relative acceleration.
- This provides the sensation of weightlessness, similar to what astronauts experience in orbit.
APPEARS IN
संबंधित प्रश्न
A body of mass 0.40 kg moving initially with a constant speed of 10 m s–1 to the north is subject to a constant force of 8.0 N directed towards the south for 30 s. Take the instant the force is applied to be t = 0, the position of the body at that time to be x = 0, and predict its position at t = –5 s, 25 s, 100 s.
Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force F = 600 N is applied to
- A,
- B along the direction of string. What is the tension in the string in each case?
You are travelling in a car. The driver suddenly applies the brakes and you are pushed forward. Why does this happen?
A car accelerates on a horizontal road due to the force exerted by.
car moving at 40 km/hr is to be stopped by applying brakes in the next 4 m. If the car weighs 2000 kg, what average force must be applied to stop it?
A particle of mass 50 g moves in a straight line. The variation of speed with time is shown in the following figure. Find the force acting on the particle at t = 2, 4 and 6 seconds.

A man has fallen into a ditch of width d and two of his friends are slowly pulling him out using a light rope and two fixed pulleys as shown in the following figure. Show that the force (assumed equal for both the friends) exerted by each friend on the road increases as the man moves up. Find the force when the man is at a depth h.
The force of buoyancy exerted by the atmosphere on a balloon is B in the upward direction and remains constant. The force of air resistance on the balloon acts opposite the direction of velocity and is proportional to it. The balloon carries a mass M and is found to fall to the earth's surface with a constant velocity v. How much mass should be removed from the balloon so that it may rise with a constant velocity v?
A constant force F = m2g/2 is applied on the block of mass m1 as shown in the following figure. The string and the pulley are light and the surface of the table is smooth. Find the acceleration of m1.

In the previous problem, suppose m2 = 2.0 kg and m3 = 3.0 kg. What should be the mass m, so that it remains at rest?
Two bodies A and B of same mass are moving with velocities v and 2v, respectively. Compare their (i) inertia and (ii) momentum.
A pebble is thrown vertically upwards with a speed of 20 m s-1. How high will it be after 2 s? (Take g = 10 m s-2)
A stone is dropped freely from the top of a tower and it reaches the ground in 4 s. Taking g = 10m s-2, calculate the height of the tower.
Calculate the velocity of a body of mass 0.5 kg, when it has a linear momentum of 5 Ns.
A motorcycle of mass 100 kg is running at 10 ms−1. If its engine develops an extra linear momentum of 2000 Ns, calculate the new velocity of a motorcycle.
Name the physical entity used for quantifying the motion of a body.
Why is it advantageous to turn before taking a long jump?
State Newton's second law of motion.
A body of mass 400 g is resting on a frictionless table. Find the acceleration of the body when acted upon by a force of 0.02 N.
A ball is thrown vertically downward with an initial velocity of 10 m/s. What is its speed 1 s later and 2 s later?
