Unit C - Circular Motion, Work, and Energy

Question 1

What force acts on passengers in a circular carnival ride

Answer 1

An inward force acts on the passengers to keep them moving along a circular path. The seat pushes on the passengers, forcing them to remain on a circular path

Question 2

Centripetal

Answer 2

An inward force / center-seeking force based on its direction

Question 3

Horizontal Plane

Answer 3

A plane perpendicular to the radius of the Earth, usually used to suggest that there is no vertical component to motion or force

Question 4

Uniform circular motion

Answer 4

The motion of an object with a constant speed along circular path

Question 5

Explain why the ball moves the way it does once the strong has been cut

Answer 5

When the ball was released, it travelled in the direction in which it was moving the moment the strong was cut. This occurs because the string is no longer pulling on the ball and Newton’s first law comes into play

Question 6

Newton’s First Law

Answer 6

A body continues in its state of rest or motion in a straight line with a constant speed unless an external, unbalanced force acts on it

Question 7

Newton’s Second Law

Answer 7

The rate of change of velocity of an object is proportional to and in the same direction as the unbalanced force acting upon it; F = ma

Question 8

Axis of Rotation

Answer 8

Imaginary line that passes through the center of rotation perpendicular to the circular motion

Question 9

If you ride through puddles after a rainfall, you’ll come home with water splashed on your back. Why?

Answer 9

As the wheel passes through the puddle, some of the water adheres to it. As the wheel rotates upward out of the puddle, excess water flies off. When it flies off, it moves along a path that is tangential to the wheel. Speed of water is determined by speed of the wheel.

Question 10

How is inward force related to speed

Answer 10

Fc = v^2; Inward force = speed squared

Question 11

Cycle

Answer 11

One complete back-and-forth motion or oscillation

Question 12

Rotation

Answer 12

One complete cycle for an object moving in a circular path

Question 13

Period

Answer 13

The time required for an object to make one complete oscillation (cycle)

Question 14

Rotational velocity can be measured indirectly by

Answer 14

Measuring the time (period (T)) it takes for one complete rotation (cycle or revolution), measured in s/cycle

Question 15

Frequency

Answer 15

The number of cycles per second, measured in hertz (Hz)

Question 16

Relationship between period and frequency

Answer 16

Inverse of each other; T = 1/f, f = 1/T

Question 17

Distance around a circle

Answer 17

Circumference (c =2πR), divided by the time it takes for one revolution (period = 5). Thus, the speed of anything with circular motion is v = 2πr/ T (r has to be in meters, T has to be in seconds)

Question 18

Centripetal acceleration depends on

Answer 18

Only the speed and radius of the circular motion, mass does not affect it. However, the larger the mass, it was experience a larger centripetal force

Question 19

If you triple the speed which you twirled a ball on a string, how would it affect the size of the inward force (tension) on in the string

Answer 19

Fc = mv^2/r. Centripetal force is calculated by mass * velocity^2 / radius. If we triple velocity 3^2 is 9, so we would increase the tension in the string by 9 times.

Question 20

Weightless

Answer 20

Experience little apparent gravitational pull

Question 21

Tension

Answer 21

A stress that tends to strech an objecet

Question 22

Vertical circular motion

Answer 22

Motion in a circular path where one diameter of the circle is vertical

Question 23

At the top and bottom of a vertical circle, the inward force is the sum of the

Answer 23

Tension and gravitational force vectors. F inwards = Ft + Fg

Question 24

At which point in the vertical circle do the tension and force due to gravity act in the same direction to produce the inward force

Answer 24

Top

Question 25

At which point in the vertical circle do the tension and force due to gravity act in the opposite direction to produce the inward force

Answer 25

Bottom

Question 26

Why does water stay in an upside down bucket

Answer 26

At the top, the inward force accelerates the bucket and its contents vertically down.As long as the bucket is moving with enough speed to maintain tension on the rope the inward force will accelerate the water more than gravity, keeping it pressed against the bottom

Question 27

What does “NaN” mean

Answer 27

When NaN is displayed, the tension has become negative (reversed directions). This symbolizes that the ball would be in freefall

Question 28

Firces acting on the bucket when its parallel to the ground

Answer 28

In this situation, gravity is perpendicular to the tension. It does not contribute to the centripetal force. Tension alone is the centripetal force

Question 29

Formula for tension

Answer 29

Mv2/r + mg

Question 30

For any solid rotating object

Answer 30

Regardless of its shape, the frequency of rotation for all points on the object will be the same. The further point has the highest speed since it has the greatest distance to cover

Question 31

Centripetal acceleration formula