Here are some short answer questions that can help you for mcq (or one mark) type problems :
SHORT QUESTION ANSWERS
2) Can a body have a constant speed but a varying velocity?t of a moving object will have the same magnitude?
Ans: It is possible only when the object moves on a straight line in the same direction.
2)Can a body have a constant speed but a varying velocity?
Ans: Yes, it is possible when the body is moving in a circular path with a uniform speed. At every point of its path, the speed is same but the velocity is directed tangentially.
4) What does the speedometer of a car measure? varying speed?
Ans: No, it is not possible because the modulus of the velocity or magnitude is the speed.
4)What does the speedometer of a car measure?
Ans: It measures instantaneous speed.
5) While firing, one has to aim a little above the target. Why?
Ans: It is because due to gravily, the bullet moves in the parabolic path. So it falls vertically and should be aimed above the target.
6) Why is time repeated twice in the unit of acceleration?
Ans: Velocity is the rate of change of displacemcnt and acceleration is the rate of change of velocity. So
acceleration is the rate of a rate. That is why time is repeated twice.
7)Can speed be negative?
Ans: No, it is not possible because it is magnitude of velocity.
8) Can the body be said to be at rest and in motion at the same time?
Ans: Yes, it is possible. Two persons inside a moving bus are at rest with respect to each other but they are in motion with respect to an observer standing on the road side.
9) In a long jump, which factors determine the span of jump?
Ans: The span of jump depends upon (i) initial velocity of projcction and (ii) the angle of projecion.
10) Ifthe magnitude and direction of the acceleration are constant, is it necessarily be a straight line path?
Ans: Not necessary. Because a projectile has constant acceleration both in magnitude and direetion, it still has parabolic path.
11) A person silting in a moving bus throws a stone vertically upward. How does the ball appear to move to an observer inside the bus? What for outside observer?
Ans: To observe inside the bus it appears moving vertically upward. However, for an observer outside the bus, the motion of the stone is parabolic.
12) What are horizontal and vertical components of acceleration of a body thrown horizontally with uniform speed?
Ans: When a body is thrown horizontally with uniform speed, then its horizontal acceleration is zero and vertical acceleration is g.
13) At what point the velocity and acceleration of a projectile are perpendicular?
Ans: At the highest point of the parabolic path, acceleration and velocity are perpendicular because the vertical component of velocity is zero and there is only horizontal component.
14) Can you give the example such that velocity is zero but acccleration is non-zero?
Ans: When an object is thrown up, then at the highest point velocity is zero but acceleration due to gravity is g.
15) Is the value of 'g' positive or negative?
Ans: Accclcration due to gravity is always vertically downward. So value of g will be negative or positive depending on the choice that upward direction is taken positive or negative.
16) Thc direction in which an object moves is given by the direction of velocity and not by the direction of acceleration. Why?
Ans: It is because when an objeci is thrown upward its direction of motion and velocity are vertically upward but the acceleration is downward as change in velocity is negative in upward direction and projectile has only horizontal velocity. So velocity gives the direction of motion not acceleration.
17) At what point, the velocity of a projectile is minimum?
Ans: It 1s minimum at the highest point because the vertical velocity becomes zero at that point and there is only the horizontal velocity.
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