Motion: Short Answer Type Questions with Answers

Problem 1. The displacement-time graph for two particles A and B are straight lines inclined at angles of 30° and 60° with the time axis. What is the ratio of velocities of V_A: V_B ?

Solution.

Problem 2. An object is projected upwards with a velocity of 100 m/s. After what time will it strike the ground?

Solution

Problem 3. A car moving with a speed of 50 km/hr. can be stopped by brakes after at least 6m. If the same car is moving at a speed of 100 km/hr, find the minimum stopping distance.

Solution.

Problem 4. A particle starts from rest. Its acceleration (a) versus time (t) is as shown in the figure. What will be the maximum speed of the particle ?

 

Solution.

The area under acceleration time graph gives change in velocity. As acceleration is zero at the end of 11 sec.

Problem 5. Can an object maintain its motion in the same direction while reversing the direction of acceleration?

Solution.

Yes, reversing the direction of acceleration will produce retardation. Consequently the velocity

will start decreasing with time but the direction of motion will be maintained till the velocity is

reduced to zero and gets reversed.

Problem 6. It is the velocity and not the acceleration which decides the direction of motion of a body.” Justify this statement with the help of a suitable example.

Solution.

The direction of velocity is always in the direction of motion of the body, whereas the direction of acceleration may or may hot be is the direction of the motion of the body.

Hence, the velocity decides the direction of motion of the body.