Rotational dynamics and kinematics mistakes

Question 1

State the direction of centripetal force

Answer 1

Towards the centre of the circle

Question 2

State effect of decrease or increase in velocity of object moving in circle hanging from string on angle Ø between string and vertical through the centre of the horizontal circle of the objects path,

Answer 2

If v decreases Ø decrease since centripetal force will decrease and weight will stay the same.
Vice versa for increase

Question 3

Why is moment of inertia greater using conservation of energy way of calculating

Answer 3

Energy is lost

Question 4

If equation has something squared the % uncertainty will be

Answer 4

Multiplied by 2

Question 5

Why when speed of sphere moving in circular path attached to string decreases will it stop travelling in circular path

Answer 5

When speed decreases the tension or centripetal force will decrease.
Weight is greater than the centripetal force that would be required for this circular motion

Question 6

Why can car travel faster in a circle on a banked track?

Answer 6

Component of reaction now acts radially, centripetal force now increases

Question 7

When asked for giving equation make sure that it is

Answer 7

Fully differentiation not just by d/dt (equation)

Question 8

When asked to find acceleration from an equation involving s=

Answer 8

Use second order differentiation

Question 9

In question where plane levels out from a previously banked circular rotation what will happen.

Answer 9

The plane will accelerate upwards as the vertical component of lift will increase and weight stay constant.

Question 10

When stating what will happen when spinning person holds mass closer to their body remember to mention:

Answer 10

That mass stays constant

Question 11

When using equations for angular motion:

Answer 11

Write them from relationship sheet very carefully and don’t be a dumb cunt