Tiêu đề UNIFORM CIRCULAR MOTION.pdf ✅

www.teachersofphysics.com Copyright © 2020 2020 TEACHERS OF PHYSICS www.teachersofphysics.com 7/15/2020 UNIFORM CIRCULAR MOTION
www.teachersofphysics.com Copyright © 2020 1. Define angular displacement.  It is the angle subtended by an arc at the center of a circular path. 2. Define a radian.  It is an angle subtended at the center of a circle by an arc length equal to the radius of the circle. 3. Define centripetal force.  It is a force that is required to keep a body moving in a circular path and is directed towards the center of the circular path. 4. Define angular velocity and state its SI unit.  It is the rate of change of angular displacement. SI unit is radian per second. 5. Distinguish between linear velocity and angular velocity. Linear Velocity Angular Velocity It is the measure of the rate of change of displacement with respect to time when an object moves along a straight path. It is the rate of change of the angular displacement. SI unit is meter per second SI unit is radian per second 6. State what is meant by centripetal acceleration.  It is the acceleration of a body towards the center of the circle. 7. Define critical speed.  It is the minimum speed that an object moving in a circular path must maintain in order to avoid skidding off the track. 8. Explain why bodies in circular motion undergo acceleration even when their speed is constant.  A body moving in a circular path is said to accelerate even if its speed is constant because its velocity keeps on changing with time as the direction also changes the rate of change of velocity. Thus resulting in acceleration. 9. Explain why the moon is said to be accelerating when revolving around the earth at constant speed.  The moon is said to be accelerating when revolving around the earth at a constant velocity because its velocity keeps on changing as the direction changes with time. This rate of change of velocity results in the moon’s acceleration. 10. State two ways in which the centripetal force on the ball in its circular motion, would be reduced.  Increasing the radius of the path.  Reducing the angular velocity of the ball. 11. What is meant by the term “Banking” in roads?  It is the act of making the road such that the outer path is slightly raised above the inner side so that the track is slopping towards the center of the curve.

www.teachersofphysics.com Copyright © 2020 17. A cyclist negotiating a corner at a high speed leans inwards in order to successfully pass. Explain how this action enables him to negotiate.  Leaning inwards produces the turning effect in the clockwise and anti-clockwise because of the normal and frictional forces thus providing sufficient centripetal force. 18. A sports car negotiates a corner on a banked road at very high velocity. i. What is meant by the term banked road?  This is a road that has the outer part slightly raised above the inner side so that the track is slopping towards the center of the curve. ii. Name two factors which determine the magnitude of its velocity.  Radius of the corner.  Banking angle.  Nature of the road surface. iii. What provides the centripetal force on the car?  Frictional force between the car tyres and the surface of the road OR Horizontal component of reaction force. 19. What provides for the centripetal force the following cases of circular motion? a) The moon moving around the earth.  Force of attraction between the earth and the moon. b) A cyclist negotiating a curve.  Frictional force between the tyre and the surface of the curve. 20. When is a satellite said to be in a “parking orbit”?  If its periodic time is equal to that of the earth. 21. State the factors affecting the centripetal force and Explain how each of the factors affect the centripetal force. a. Mass of the body → , . b. Angular velocity of the object → , c. Radius of the path →