Q.1. Are rest and motion absolute or relative terms?
AnswerAnswer: Yes, both rest and motion are relative terms. An object at rest in one frame of reference can be in motion in another frame of reference.
Q.2. Can an object be at rest as well as in motion at the same time?
AnswerAnswer: Yes. A body may be at rest relative to one object and at the same time it may be in motion relative to another object.
Q.3. What is uniform motion?
AnswerAnswer: If a body has equal displacements in equal intervals of time, the motion is called uniform motion. The velocity of motion will be a constant in this case.
Q.4. What do you get from area under (v-t) graph?
AnswerAnswer: Area under v-t graph gives displacement.
Q.5. What will be nature of x-t graph for a uniform motion?
AnswerAnswer: It will be a straight line, inclined with time axis.
Q.6. How can the distance travelled be calculated from v-t graph?
AnswerAnswer: The area under v-t graph for a given time interval is numerically equal to the distance covered by the body in that time interval.
Q.7. Consider that the acceleration of a moving body varies with time. What does the area under acceleration-time graph for any time interval represent?
AnswerAnswer: The area under acceleration-time graph for any time interval represents the change of speed of the body during that time interval.
Q.8. A ball is thrown straight up. What is its velocity and acceleration at the top?
AnswerAnswer: At the highest point, the velocity of the ball is zero and its acceleration is equal to acceleration due to gravity acting in the downward direction.
Q.9. Give an example which shows that a negative acceleration can be associated with a speeding up object.
AnswerAnswer: An object in simple harmonic motion speeds up while moving from an extreme position to the mean position but its acceleration is negative.
Q.10. What is the ratio of the time taken to go up and come down by a body thrown vertically up?
AnswerAnswer: 1 : 1 in the absence of air resistance.
Q.11. What can you say about the nature of acceleration, associated with a mass whose v-t graph is shown?
AnswerAnswer: The slope is same. So acceleration is constant.
Q.12. What does the speedometer record – the average speed or instantaneous speed ?
AnswerAnswer: Instantaneous speed.
Q.13. Can a body moving with a uniform velocity be in equilibrium?
AnswerAnswer: Yes, since the net force acting on it is zero.
Q.14. Two particles A and B are moving along the same straight line with B ahead of A. Velocity remaining unchanged, what would be the effect on the magnitude of relative velocity, if A is ahead of B?
AnswerAnswer: No effect.
Q.15. Under what condition the average velocity of a body is equal to its instantaneous velocity?
AnswerAnswer: When the body is moving with constant velocity, the average velocity of a body is equal to its instantaneous velocity.
Q.16. When is the magnitude of average velocity same as that of average speed?
AnswerAnswer: When the body is moving with a constant velocity, the magnitude of average velocity is same as that of average speed.
Q.17. Identify the type of motions? (a) a carom coin is striking against the side of a board and not rebounding smoothly but hoping up as it rebounds, (b) a car going along a zigzag path on a road.
AnswerAnswer: (a) Three dimensional motion (b) Two dimensional motion
Q.18. Can a particle have varying speed but a constant velocity?
AnswerAnswer: No since both speed and velocity remain constant in uniform motion.
Q.19. What is the acceleration of a particle moving with uniform velocity?
Q.20. Under what condition will the distance and displacement of a moving object have the same magnitude?