YR2 LINEAR MOTION & ANGULAR

Question 1

What is linear motion?

Answer 1

The movement of a body in a straight or curved line, where all the parts move the same
distance in the same direction in the same time

Question 2

What is linear motion caused by?

Answer 2

Linear motion is caused from a direct force applied to the Centre of a body’s mass (the point at which a body is balanced in all directions (weight acts from this
point)

Question 3

What is distance?

Answer 3

The total length covered from start to distance in positions (m)

Question 4

What is displacement?

Answer 4

The shortest straight line distance from start to finish

positions (m)

Question 5

What is speed?

Equation?

Answer 5

The rate of change is distance (m/s)

Speed = Distance ÷ Time taken

Question 6

What is velocity?

Equation?

Answer 6

The rate of change is displacement (m/s)

Speed = Displacement ÷ Time taken

Question 7

What is acceleration?

Equation?

Answer 7

The rate of change in velocity (ms-2)

Acceleration = (Final Velocity –Initial Velocity) ÷ Time taken

Question 8

Positive Value =

Negative value =

Answer 8

Acceleration

Deceleration

Question 9

Tips for DISTANCE TIME GRAPHS?

Answer 9

Cannot go down (distance cannot decrease)

Gradient is equal to the speed

Question 10

Tips for VELOCITY TIME GRAPHS?

Answer 10

Curves show acceleration

Can be positive and negative

Question 11

Tips for SPEED TIME GRAPHS?

Answer 11

Area under is the distance

Positive gradient acceleration negative deceleration

Question 12

What is Angular motion?

What is it caused by?

Answer 12

Movement of a body or part of a body in a circular path about an axis of rotation

Angular motion is caused from a eccentric force , a force that is applied outside the
center of mass. An eccentric force is also known as torque, a measure of turning
force applied to a body

Question 13

What is a sporting example of angular motion?

Answer 13

E.g. a trampolinist body will rotate around her center of mass in a somersault

Question 14

Name 3 axis of rotation?

Answer 14

Longitudinal
Frontal
Transverse

Question 15

What is Longitudinal axis:?

Example

Answer 15

Running from head to toe through the center of mass.

A performer rotates around this axis in a flat spin on the
ice during ice dance

Question 16

What is Transverse axis?

Example

Answer 16

Running from left to right through the center of mass.

A performer rotates around this axis in a somersault
in a vault

Question 17

What is Frontal axis?

Example

Answer 17

Running from back to front through the center of mass.

A performer rotates around this axis in a cartwheel

Question 18

What are the three Angular motion descriptors?

Answer 18

Angular Velocity

Moment of inertia

Angular Momentum

Question 19

What is Angular velocity?

Equation?

Measured in?

Answer 19

The rate of rotation-

Angular velocity = angular displacement/time taken

Measured in Radians (rad)

Question 20

What is moment of inertia?

Equation?

Answer 20

The resistance of a body to change in its state of angular motion or rotation

Moment of inertia = sum of ( mass x distribution of the mass from the axis of rotation squared)

Question 21

What two factors affect the moment of inertia?

Answer 21

Mass

Distribution of mass

Question 22

How does mass affect the moment of inertia?

Answer 22

The higher the mass the higher the moment of inertia (why all gymnasts are small)

The lower the mass the lower the moment of inertia (Rugby props are never small)

Question 23

How does distribution of mass affect moment of inertia?

Answer 23

The higher the distribution of mass the higher the moment of inertia (why pike flips are harder than
somersaults)

The lower the distribution of mass the lower the moment of inertia

Question 24

When running -

Drive Phase

Recovery Phase

High or low MOI?

Answer 24

Drive phase:
High MI
Large distribution of mass

Recovery Phase:
Low MI
Low distribution of mass

Question 25

HOW CAN MOMENT OF INERTIA BE

MANIPULATED?

Answer 25

Moment of inertia has a direct impact on velocity:

If there is a high MI then resistance to rotation of high so angular velocity is
slow

If there is a low MI then there is not much resistance to rotation so angular
velocity is high

Question 26

What is angular momentum?

Equation?

Answer 26

The quantity of angular motion possessed by a
body

Angular momentum (kgm2s-1) =
Moment of inertia x angular velocity

Question 27

What is the CONSERVATION OF ANGULAR

MOMENTUM?

Answer 27

Newton’s Law of inertia: constant velocity until acted upon by an external force

So angular momentum is constant, it cannot be generated during flight but can be
manipulated during flight to allow for velocity changes.

Increase the distribution of mass, you decrease moment of inertia and therefore can decrease velocity to keep angular momentum constant

Question 28

CONSERVATION OF ANGULAR

MOMENTUM sporting example?

Answer 28

E.G. Tom Daley cannot increase angular momentum mid flight but can increase and decrease velocity due to a manipulation of the equation

Question 29

Describe the way in which an ice skater
performing a triple axel jump with spin
achieves this using, axis of rotation, angular
velocity and angular momentum?

Answer 29

The Ice skater generates angular motion by applying an eccentric force

The Ice skater starts rotation around the longitudinal axis

The distribution of mass is large so the moment of inertia is increased and angular
velocity it low so they stay in control

The distribution of mass is small so the velocity increases and moment of inertia
decreases (allows for more spins)

The distribution of mass is large so the moment of inertia is increased and angular
velocity lowers, increasing their control for landing

As they land the ice applies external force to remove the angular momentum