Advertisements
Advertisements
Question
Give a scientific reason.
When an object falls freely to the ground, its acceleration is uniform.
Advertisements
Solution
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.
APPEARS IN
RELATED QUESTIONS
An object of mass 16 kg is moving with an acceleration of 3 m/s2. Calculate the applied force. If the same force is applied to an object of mass 24 kg, how much will be the acceleration?
The velocity-time graph for a uniformly retarded body is a straight line inclined to the time axis with an obtuse angle. How is retardation calculated from the velocity-time graph?
Figure given below shows a velocity-time graph for a car starting from rest. The graph has three parts AB, BC and CD.

(a) Is the magnitude of acceleration higher or lower than that of retardation ? Give a reason .
(b) Compare the magnitude of acceleration and retardation .
A bullet initially moving with a velocity 20 m/s strikes a target and comes to rest after penetrating a distance 10 cm into the target. Calculate the retardation caused by the target.
When is the acceleration due to gravity positive?
Draw velocity – time graph for the following situation:
When a body is moving with variable velocity and variable acceleration.
A racing car is moving with a velocity of 50 m/s. On
applying brakes, it is uniformly retarded and comes to rest in 20 seconds. Calculate its acceleration.
Diagram is given below shows velocity – time graph of car P and Q, starting from the same place and in the same direction. Calculate the Acceleration of car Q between 2 s – 5 s.

An aeroplane lands at 216 kmh−1 and stops after covering a runway of 2 m. Calculate the acceleration and the time, in which it comes to rest.
A motor bike running at 5 ms−1, picks up a velocity of 30 ms−1 in 5s. Calculate
- acceleration
- distance covered during acceleration.
Write the SI unit of acceleration and retardation.
The distance covered by a body is directly proportional to the square of the time elapsed. What can you say about its acceleration?
State if the following situation is possible:
A body moving horizontally with an acceleration in vertical direction.
What happens to the stepwise increasing speed-time graph when the size of each step is made very small?
A car accelerates to a velocity of 30 m/s in 10 s and then decelerates for 20 s so that it stops. Draw a velocity-time graph to represent the motion and find:
Distance travelled
What do you understand about negative acceleration?
A bus accelerating with 4ms-2 changes its speed from 60ms_1 to a certain value in 5s. The final speed is ______.
A boy throws a ball up and catches it when the ball falls back. In which part of the motion the ball is accelerating?
A car is being driven at a speed of 20ms-1 when brakes are applied to bring it to rest in 5 s. The deceleration produced in this case will be ______.
