Circular Motion

Question 1

define angular displacement

Answer 1

the angle through which an object moves in a circle

Question 2

define the radian

Answer 2

the angle subtended at the centre of a circle by an arc of length equal to the radius of the circle

Question 3

how do you convert from degrees to radians?

Answer 3

multiply by pi/180

Question 4

how do you convert from radians to degrees?

Answer 4

multiply by 180/pi

Question 5

define centripetal force

Answer 5

the net force acting on an object moving in a circle; it is always directed towards the centre of the circle

Question 6

how can an object have steady speed but changing velocity?

Answer 6

because velocity is a vector quantity and so changes when the object changes direction, unlike speed

Question 7

at what angle is the force to the velocity of an object travelling in a circle?

Answer 7

90 degrees. This explains how the speed does not change. For the speed to change there must be a force in the direction the object is travelling, but a force at 90 degrees to the velocity means it has no component in the required direction

Question 8

what is the equation for calculating the centripetal force of an object?

Answer 8

F= (mv^2)/r

Question 9

what is the equation for calculating the centripetal acceleration of an object?

Answer 9

a= v^2/r

Question 10

how do you calculate orbital speed?

Answer 10

replace “a” in the centripetal acceleration equation for g (9.81) and rearrange
9.81= (mv^2)/r

Question 11

is an object moving in a circle in equilibrium?

Answer 11

no, it has a net force acting on it