5.2 Circular Motion

Question 1

Define radian

Answer 1

Unit of angle, where 2π is equal to one complete angular rotation.

Question 2

Convert from degrees to radians

Answer 2

Multiply by π/180

Question 3

Convert from radians to degrees

Answer 3

Multiply by 180/π

Question 4

What is the difference between the period (T) and the frequency (f)? [In terms of circular motion]

Answer 4

Period is the time taken for an object to travel a full circle.
Frequency is the number of full circles completed in one second.

Question 5

Define the angular velocity of an object.

Answer 5

The rate of change of angle.

Question 6

What is the formula and units for angular velocity?

Answer 6

ω = 2π/T = 2πf
rad s-1

Question 7

Explain why an object moving around in a circle is always accelerating. [3]

Answer 7

When an object travels in a circle, the direction is constantly changing.
Velocity is given with respect to direction, meaning the velocity is also constantly changing.
In order for the velocity to change, the object must be accelerating.

Question 8

An object travelling around in a circle will always be accelerating. What type of force provides this acceleration?

Answer 8

Centripetal force.

Question 9

Define centripetal force.

Answer 9

The net force which acts perpendicular to the direction of the velocity, towards the centre of the circle.

Question 10

The speed v of an object moving in a circle of radius r is given by what formula?

Answer 10

v = 2πr / t = ωr

Question 11

When an object experiences many forces, and we want to find the centripetal force, what force do we use?

Answer 11

The resultant force.