PhysicsPhysics
Circular Motion
CircularCircular motionmotion
• Revision
• Circular motion in horizontal
• Vertical circular motion
• Loop-the-loop
RevisionRevision
• Newton’s Laws
• Circular motion in horizontal circles
• Centripetal force and acceleration
• Angular velocity, frequency & linear velocity
Newton’s first LawNewton’s first Law
A body continues in a state of
rest or uniform motion in a
straight line unless it is acted
upon by external forces.
No external forceThe body remains at rest.
The body moves with a constant speed.
Newton’s first LawNewton’s first Law
The rate of change of momentum
of a body is proportional to and
in the same direction as the
resultant force that acts on it.
constant is m if ma F dt
(mv) d F net
Newton’s second LawNewton’s second Law
For fixed forceA body with a larger mass moves with a smaller acceleration .
A body with a smaller mass moves with a larger acceleration .
Newton’s second LawNewton’s second Law
For fixed massA body with a smaller net force moves with a smaller acceleration .
A body with a larger net force moves with a larger acceleration .
Newton’s second LawNewton’s second Law
If one body exerts a force on
another, there is an equal and
opposite force, called reaction,
exerted on the first body.
Newton’s third LawNewton’s third Law
Body A exerts a force on body B, then body B exerts an equal and opposite force on body A.
Newton’s third LawNewton’s third Law
Body A Body B
Force on B by AForce on A by B
Newton’s third LawNewton’s third Law
Circular Motion in horizontal circlesCircular Motion in horizontal circles
Circular Motion in horizontal circlesCircular Motion in horizontal circles
Angular velocity = / t
Linear velocity v = r Centripetal force
F = m r 2 = m v2 / r
Centripetal accelerationa = r 2 = v2 / r
Circular Motion in horizontal circlesCircular Motion in horizontal circlesConical pendulumConical pendulum
Circular Motion in horizontal circlesCircular Motion in horizontal circlesConical pendulumConical pendulum
Do you remember what kind of forces provides the centripetal force to the bob ?
Tension T
Weight mg
Centripetal force
Vertical circular motion Vertical circular motion Bucket and waterBucket and water
Does the water spill out the bucket when whirling ?
If no, why doesn’t it spill out ?
Vertical circular motion Vertical circular motion Bucket and waterBucket and water
What kind of motion does thebucket perform ?
Vertical circular motion
What kind of force provides the centripetal force Fc to thebucket ?
Tension T
Weight mg
Vertical circular motion Vertical circular motion Bucket and waterBucket and water
What kind of force providesthe centripetal force Fc to the bucket at the highest position ?
Fc = T + mg
Tension T Weight mg
Vertical circular motion Vertical circular motion Bucket and waterBucket and water
What kind of force providesthe centripetal force Fc to the bucket at the lowest position ?
Fc = T - mgTension T Weight
mg
Vertical circular motion Vertical circular motion Bucket and waterBucket and water
What kind of force provides the centripetal force Fc to the water at the highest position ?
Fc = R + W Reaction of the bucket
R
Weight of water
W
Vertical circular motion Vertical circular motion Bucket and waterBucket and water
What kind of force providesthe centripetal force Fc to the bucket at the lowest position ?
Fc = R - W
Reaction of the bucket
R
Weight of water
W
Vertical circular motion Vertical circular motion Loop-the-loopLoop-the-loop
Vertical circular motion Vertical circular motion Loop-the-loopLoop-the-loop
What kind of force providesthe centripetal force Fc to the mass ?
The reaction of the track
M.C. Exercise
Class Class exercisesexercises
Mainmenu
True or False
M.C. Question 1
Which of the following formula
shows Newton’s second Law ?
v = r = / tF = maa = v2 / r
M.C. Question 2
At which position is the tension
on the bucket largest ?
True or False Question 1
True False
If the angular velocity of the bucket
at the top position is too small,
water may spill out.
True False
In the Ocean Park , cart coast rider
can loop the loop by tension.
True or False Question 2
Top Related