16.1 - 16.3

Question 1

define angular velocity

Answer 1

the rate of change of the angle when moving in a circular path. measured in rad s^-1

Question 2

define centripetal force

Answer 2

a force the keeps a body moving with a constant speed in a circular path

Question 3

why does centripetal force cause no change in speed

Answer 3

it acts perpendicular to the velocity. there is no component acting in the direction of travel so no work is done keeping the speed constant

Question 4

which direction is the velocity when an object is moving in a circular path

Answer 4

at a tangent to the point on the circle where the object is

Question 5

relationship between linear velocity and radius for an object with circular motion

Answer 5

if angular velocity is constant then the linear velocity is directly proportional to the radius

Question 6

define centripetal acceleration

Answer 6

the acceleration of an object travelling in a circular path with a constant speed. it acts towards the centre of the circle

Question 7

why should cars slow down when turning corners

Answer 7

the greater the speed of the car the greater the centripetal force needed to travel in the same circular path. they slow so the friction between the tyre and the road is sufficient. if the car is too fast the turning radius increases so it doesn’t follow the road

Question 8

why are bike tracks sloped

Answer 8

so the horizontal component of the weight combined with the friction from the tyres provides a greater centripetal force. this allows greater speeds when turning

Question 9

how does the normal contact force(N) change when on a Ferris wheel and why

Answer 9

when stationary N equals your weight. a net force is needed for circular motion so it changes when moving. at the top, N is smaller and at the bottom, N is larger. this is so the resultant force is towards the centre