Circular motion (1)

Question 1

Newton’s 1st law of motion

Answer 1

a body remains at rest or continues to move in a straight line at a constant speed unless acted on by an unbalanced force.

Question 2

Radian

Answer 2

the radian measure of a central angle of circle, θ, is defined as the ratio of the arc length, s, subtended by the angle θ, to the radius r: θ=s/r

Question 3

Angular displacement

Answer 3

the angle (measured in radians, rad) through which a line rotates about a fixed point.

Question 4

Angular velocity, ω

Answer 4

the rate of change of angular displacement (measured in radians per second, rads-1)

Question 5

Centripetal acceleration

Answer 5

when a particle moves in a circular path of radius r, at a constant speed v, there must be a centripetal acceleration towards the centre of the circle.

Question 6

Centripetal force

Answer 6

when an object moves around a circular path, there must be a centripetal force acting towards the centre of the circle. Something must provide this force, such as a pull from a string or a push from the road.