Give scientific reasons.a. When an object falls freely to the ground, its acceleration is uniform.
b. Even though the magnitudes of action force and reaction force are equal and their directions are opposite, their effects do not get cancelled.c. It is easier to stop a tennis ball as compared to a cricket ball when both are travelling with the same velocity.d. The velocity of an object at rest is considered to be uniform.
b. Even though the magnitudes of action force and reaction force are equal and their directions are opposite, their effects do not get cancelled.
a. When an object falls freely to the ground, it is under the effect of a constant force known as the force of gravity. No other forces act on it. Hence, from Newton's second law of motion, we can say that this constant force of gravity accelerates the freely falling object uniformly. This uniform acceleration is known as acceleration due to gravity which acts towards the centre and is denoted by g.
b. When two bodies interact, the action and reaction forces come into action. Even though their magnitude are the same and their direction is opposite, their effects do not get cancelled because these action and reaction forces do not act on the same body.
c. Momentum of a body is the product of its mass and velocity i.e.
p=mv
and the rate of change of momentum of a body is equal to the force applied i.e.
F=m(v−u)t
In the given information, both the balls move with the same velocity and finally stops, thus the force applied to stop the ball will be directly proportional to the mass of the ball.
F∝m
As the mass of the cricket ball is greater than the tennis ball, its momentum will be more than the tennis ball. Thus, a greater force will be required to stop the cricket ball as compared to that of a tennis ball.
d. Velocity of an object is said to be uniform when its speed and direction do not change. The object at rest has a uniform speed of zero all the time and does not even change the direction. Hence, the velocity of an object at rest is considered to be uniform.
a. When an object falls freely to the ground, it is under the effect of a constant force known as the force of gravity. No other forces act on it. Hence, from Newton's second law of motion, we can say that this constant force of gravity accelerates the freely falling object uniformly. This uniform acceleration is known as acceleration due to gravity which acts towards the centre and is denoted by g.
b. When two bodies interact, the action and reaction forces come into action. Even though their magnitude are the same and their direction is opposite, their effects do not get cancelled because these action and reaction forces do not act on the same body.
c. Momentum of a body is the product of its mass and velocity i.e.
p=mv
and the rate of change of momentum of a body is equal to the force applied i.e.
F=m(v−u)t
In the given information, both the balls move with the same velocity and finally stops, thus the force applied to stop the ball will be directly proportional to the mass of the ball.
F∝m
As the mass of the cricket ball is greater than the tennis ball, its momentum will be more than the tennis ball. Thus, a greater force will be required to stop the cricket ball as compared to that of a tennis ball.
d. Velocity of an object is said to be uniform when its speed and direction do not change. The object at rest has a uniform speed of zero all the time and does not even change the direction. Hence, the velocity of an object at rest is considered to be uniform.
