A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, (a) during its upward motion, (b) during its downward motion, (c) at the highest point where it is momentarily at rest. Do your answers change if the pebble was thrown at an angle of 45° with the horizontal direction? Ignore air resistance.
(a)
Given: The mass of the pebble is 0.05 kg .
We know that the acceleration due to gravity always acts in the downward direction irrespective of the direction of motion of the pebble.
The gravitational force is only responsible for acceleration or deceleration of the pebble.
Newton’s second law of motion is given as,
F = m g
By substituting the given values in the above expression, we get
F = ( 0.05 kg ) ( 10 m / s 2 ) = 0.5 N
A force of 0.5 N is acting in the upward direction for all the cases.
When the pebble moves upward, the gravitational force acts in the downward direction and the velocity of the pebble starts reducing.
(b)
When the pebble moves downward, the gravitational force of 0.5 N acts in the downward direction and the velocity of the pebble start increasing.
(c)
When the pebble is at the highest point, the gravitational force of 0.5 N acts in the downward direction and the velocity of the pebble is zero.
No, the answers do not change when the pebble is thrown at an angle of 45 ° with the horizontal. This is because the acceleration due to gravity always acts in the downward direction.
When the pebble is thrown at an angle of 45 ° , it has both horizontal and vertical components of velocity. The horizontal component remains constant throughout the motion of the pebble. The vertical component becomes zero at the highest point.
Whether it is upward flight, highest point or downward flight, the force of 0.5 N will act on the pebble in the downward direction.
(a)
Given: The mass of the pebble is
We know that the acceleration due to gravity always acts in the downward direction irrespective of the direction of motion of the pebble.
The gravitational force is only responsible for acceleration or deceleration of the pebble.
Newton’s second law of motion is given as,
By substituting the given values in the above expression, we get
A force of
When the pebble moves upward, the gravitational force acts in the downward direction and the velocity of the pebble starts reducing.
(b)
When the pebble moves downward, the gravitational force of
(c)
When the pebble is at the highest point, the gravitational force of
No, the answers do not change when the pebble is thrown at an angle of
When the pebble is thrown at an angle of
Whether it is upward flight, highest point or downward flight, the force of
