Motion in a circle

Question 1

Radian def

Answer 1

One radian is the angle subtended at the centre of a circle such that the arc length is equal to the radius

Question 2

Angular displacement formula

Answer 2

θ= s/r

Question 3

Angular speed def

Answer 3

angle swept out by the radius per unit time

Question 4

Speed v of an object travelling around a circle depends on which two quantities?

Answer 4

• angular speed
• distance from centre of the cirlce

Question 5

Why is speed constant during circular motion?

Answer 5

No component of force acting in direction with velocity

Question 6

angular speed formula (2)

Answer 6

ω= v/r
ω= 2π/ T

Question 7

What causes centripetal acceleration (2)

Answer 7

A force of constant magnitude that is always perpendicular to the direction of motion

Changing velocity, due to changing direction, therefore acceleration

Question 8

What causes uniform circular motion ? (2)

Answer 8

• Acceleration always perpendicular to velocity
• Constant speed

Question 9

Formulas for centripetal acceleration

(2)

Answer 9

a= v²/ r
a= ω²r

a= vω

Question 10

Resultant force formulas

(2)

Answer 10

F= mv²/ r
F= mω²r

Question 11

Centripetal acceleration

Answer 11

Acceleration perpendicular to velocity

Question 12

Centripetal force

Answer 12

resultant force on an object towards centre of object when rotating round circle and speed is constant

centripetal force itself is not a force, it describes another force

Question 13

To calculate orbital speed?

Answer 13

mg=mv²/ r

find v