Horizontal circular motion
- Lesson: 113:15
- Lesson: 212:08
Horizontal circular motion
Lessons
In this lesson, we will learn:
Notes:
Centripetal Acceleration
- Meaning of uniform circular motion
- Solving problems involving horizontal circular motion
Notes:
- An object moving in a circular path is in circular motion. If the speed of the object is constant, it is uniform circular motion.
- An object in uniform circular motion does experience acceleration, even though its speed is constant. Remember, acceleration is change in velocity, and a velocity is made up of speed and direction. For the object to move in a circle, the direction of its velocity must change constantly. This change in direction is the acceleration, called centripetal acceleration ("centripetal" means "towards the center"). For an object moving in a circular path, the centripetal acceleration vector is always pointed towards the center of the circle.
- Like any other type of acceleration, centripetal acceleration is caused by a force (called centripetal force). The centripetal force vector also always points towards the center of the circle.
- In order for an object to be moving in a circular path, the net force acting on the object must be a centripetal force (a force that always is pointed towards the center). When multiple forces act on an object in circular motion, those forces must add up to a centripetal force. It is important to understand that centripetal force is not a separate force that acts on an object. It is a net force which follows a specific rule: it always points towards the center of the circular path.
- In a horizontal circular motion problem, any forces acting on the object in the vertical direction must balance so that ΣFvertical=0N (otherwise the object would accelerate vertically). Only horizontal forces will contribute to the net force causing circular motion.
T=#ofrevolutionstotaltime
f=totaltime#ofrevolutions
T=f1
T: period, in seconds (s)
f: frequency, in hertz (Hz)
Centripetal Acceleration
ac=rv2=T24π2r
ac: centripetal acceleration, in meters per second squared (m/s2)
v: velocity, in meters per second (m/s)
r: radius, in meters (m)
T: period, in seconds (s)
- 1.Ball on horizontal string moving in circular motion
A 0.525 kg ball is attached to a 1.25 m string and swings in a circular path, making 2.00 revolutions per second. The angle of the string is nearly horizontal. Find the tension in the string.
- 2.Ball on angled string in horizontal circular motion
A 0.525 kg ball is attached to a 1.25 m string and swings in a circular path. The angle of the string away from vertical is 30.0°. Find the centripetal force acting on the ball and the speed of the ball.