IX Physics Ch: Motion and Rest
CBSE chapterwise MCQ Multiple Choice Questions , Test Paper , Sample paper on CCE pattern for class 9th (IX) science: Motion. Distance and displacement , velocity ; uniform and nonuniform motion along a straight line; acceleration, distancetime and velocity  time graphs for uniform motion and uniformly accelerated motion, equations of motion by graphical method; elementary idea of uniform circular motion. IX Physics Motion and Rest Notes Download File
9th physics Motion and Rest CBSE Test paper 1
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IX Physics Motion and Rest solved Numerical1
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Q. What do you mean by circular motion?
Ans: The uniform circular motion describes as the motion of an object in a circular path with a constant speed. When an object is moved in circular path then its direction is changed continues with constant speed. Or it is moved in the tangent direction of the circle while the velocity is in the direction of motion of an object which is also in the tangential direction.
Q.Define Angular displacement and angular velocity of a body moving in circular path
Ans: The angular displacement of a particle moving along a circular path is defined as the angle subtended at the center by the radius vector in the given time interval.
If a particle moves in a circular track of radius R and it swept an angle q in the time t, then we say that the angular displacement is q. If it travels a distance S in the form of an arc , then the angular displacement = Q(theta) = S/R
Angular displacement is measured in radian.
Angular velocity : The rate of change of angular displacement of a particle with respect to time when it is moving around a circular track of radius R is called angular velocity. Angular velocity is denoted by w. The unit of angular velocity is radian per second
Q. A body moves around the sun with constant speed in circular path. Is the motion of the body uniform or accelerated?
Ans: Accelerated motion because velocity changes as the direction of motion in circular path continually changes.
Q. Name the physical quantity which remains constant during uniform circular motion.
Ans: Speed
Q. Name the physical quantity which changes during uniform circular motion.
Ans: Velocity
Q. Under what condition, the average speed is equal to the magnitude of the average velocity.
Ans: If the body is moving along the straight line with constant velocity then the magnitude of average velocity is equal to its average speed.
Q. Can the average speed of a moving body be zero? Give reason
Ans: No.This is because distance cannot ne zero.
Q. Can the average velocity of a moving body be zero? State examples.
Ans: yes This is because displacement can be zero. For examples – if body return to same initial position during motion
Q. Name the two physical quantities apart from velocity and time which can be obtained from velocitytime graph.
Ans: Acceleration and displacement
Q. State which of the following situations are possible and give an example of each of these:
(a) A body moving with constant acceleration but with zero velocity.
(b) A body moving horizontally with acceleration in vertical direction.
(c) A body moving with a constant speed in an accelerated motion. 2014 SA1
Ans:
(a) When a body is thrown vertically upward in space, then at the highest point, the body has zero velocity but the acceleration of the body will be equal to the acceleration due to gravity.
(b) A body moving horizontally with acceleration in vertical direction is possible in a projectile motion.
(c) A body moving with a constant velocity in an accelerated motion is possible in a uniform circular motion.
Q. State with reasons, if it is possible or impossible, for an object in motion to have: 2015 SA1
(a) Zero distance covered and may have non zero displacement.
(b) Zero speed at an instant but non zero acceleration at the same time.
(c) Zero speed and may have non zero velocity.
(d) Acceleration opposite to the direction of motion.
(e) Positive acceleration while speeding up.
Ans:
(a) Zero distance covered and may have non zero displacement. – Impossible as distance of moving body cannot be zero
(b) Zero speed at an instant but non zero acceleration at the same time. Possible: if a ball is thrown vertically upward , At the highest point speed is zero but acceleration is non zero.
(c) Zero speed and may have non zero velocity. Impossible – if a body has none zero velocity must have speed
(d) Acceleration opposite to the direction of motion. Possible: : when a moving car applies the break its velocity decreases. The acceleration is against the direction of motion of the car.
(e) Positive acceleration while speeding up : Possible because acceleration is the rate of the change in velocity (vu/t)
Ans: The uniform circular motion describes as the motion of an object in a circular path with a constant speed. When an object is moved in circular path then its direction is changed continues with constant speed. Or it is moved in the tangent direction of the circle while the velocity is in the direction of motion of an object which is also in the tangential direction.
Q.Define Angular displacement and angular velocity of a body moving in circular path
Ans: The angular displacement of a particle moving along a circular path is defined as the angle subtended at the center by the radius vector in the given time interval.
If a particle moves in a circular track of radius R and it swept an angle q in the time t, then we say that the angular displacement is q. If it travels a distance S in the form of an arc , then the angular displacement = Q(theta) = S/R
Angular displacement is measured in radian.
Angular velocity : The rate of change of angular displacement of a particle with respect to time when it is moving around a circular track of radius R is called angular velocity. Angular velocity is denoted by w. The unit of angular velocity is radian per second
Q. A body moves around the sun with constant speed in circular path. Is the motion of the body uniform or accelerated?
Ans: Accelerated motion because velocity changes as the direction of motion in circular path continually changes.
Q. Name the physical quantity which remains constant during uniform circular motion.
Ans: Speed
Q. Name the physical quantity which changes during uniform circular motion.
Ans: Velocity
Q. Under what condition, the average speed is equal to the magnitude of the average velocity.
Ans: If the body is moving along the straight line with constant velocity then the magnitude of average velocity is equal to its average speed.
Q. Can the average speed of a moving body be zero? Give reason
Ans: No.This is because distance cannot ne zero.
Q. Can the average velocity of a moving body be zero? State examples.
Ans: yes This is because displacement can be zero. For examples – if body return to same initial position during motion
Q. Name the two physical quantities apart from velocity and time which can be obtained from velocitytime graph.
Ans: Acceleration and displacement
Q. State which of the following situations are possible and give an example of each of these:
(a) A body moving with constant acceleration but with zero velocity.
(b) A body moving horizontally with acceleration in vertical direction.
(c) A body moving with a constant speed in an accelerated motion. 2014 SA1
Ans:
(a) When a body is thrown vertically upward in space, then at the highest point, the body has zero velocity but the acceleration of the body will be equal to the acceleration due to gravity.
(b) A body moving horizontally with acceleration in vertical direction is possible in a projectile motion.
(c) A body moving with a constant velocity in an accelerated motion is possible in a uniform circular motion.
Q. State with reasons, if it is possible or impossible, for an object in motion to have: 2015 SA1
(a) Zero distance covered and may have non zero displacement.
(b) Zero speed at an instant but non zero acceleration at the same time.
(c) Zero speed and may have non zero velocity.
(d) Acceleration opposite to the direction of motion.
(e) Positive acceleration while speeding up.
Ans:
(a) Zero distance covered and may have non zero displacement. – Impossible as distance of moving body cannot be zero
(b) Zero speed at an instant but non zero acceleration at the same time. Possible: if a ball is thrown vertically upward , At the highest point speed is zero but acceleration is non zero.
(c) Zero speed and may have non zero velocity. Impossible – if a body has none zero velocity must have speed
(d) Acceleration opposite to the direction of motion. Possible: : when a moving car applies the break its velocity decreases. The acceleration is against the direction of motion of the car.
(e) Positive acceleration while speeding up : Possible because acceleration is the rate of the change in velocity (vu/t)
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