Forces, Friction and Newtons laws

Question 1

What is Newtons 1st Law?

Answer 1

Law of Inertia: An object will stay at rest or in uniform motion until a force acts on it

Question 2

What is Newtons 2nd Law?

Answer 2

Law of Acceleration: The change of motion of an object is directly proportional and in the same direction as the force acting on it

Question 3

What is Newtons 3rd Law?

Answer 3

Law of Action-Reaction: To every action there is an equal and opposite reaction

Question 4

Define inertia

Answer 4

An objects reluctance to chnage its state of motion

Question 5

Define acceleration

Answer 5

The rate of change of velocity

Question 6

Define velocity

Answer 6

Speed in a given direction

Question 7

Define speed

Answer 7

distance covered/ time

Question 8

Define a force

Answer 8

Something that can cause an object to start, stop, speed up, slow down or change direction

Question 9

What are the key purposes of measuring force in sport? (4)

Answer 9

Comparing physical capabilities
Monitor improvements
Knowledge of the force requirements to complete sporting actions
Injury prevention

Question 10

What 2 types of external forces are there?

Answer 10

Contact

Non Contact

Question 11

Define an internal force

Answer 11

A force exerted by one body part onto another

Question 12

Define an external force

Answer 12

Forces from outside the body

eg gravity

Question 13

Give 3 examples of external contact forces

Answer 13

People, objects
Fluid resistance
Ground - Friction, reaction

Question 14

Why is friction required

Answer 14

To move an object / person horizontally

Question 15

What are the 2 types of friction called

Answer 15

Static

Dynamic

Question 16

Define static friction

Answer 16

Occurs between two surfaces that are not moving relative to each other

Question 17

Define dynamic friction

Answer 17

Occurs between two surfaces that are moving relative to each other

Question 18

what is the equation for friction?

Answer 18

F(s/d) = µ(s/d) x N

Question 19

What is the friction coefficient of a surface?

Answer 19

How rough or smooth it is

Question 20

What law is GRF based on?

Answer 20

Newtons 3rd law

as we push on the ground the ground pushed back with an equal and opposite force

Question 21

What 2 contact forces are responsible for movement

Answer 21

Vertical ground reaction force (Fz)

Horizontal ground reaction force (Fy)

Question 22

What is the equation for weight

Answer 22

weight = mass x acceleration

Question 23

What is weight measure in?

Answer 23

Newtons

Question 24

How do you calculate the resultant force?

Answer 24

Vector addition

Question 25

What does the resultant force show

Answer 25

Magnitude and direction

Question 26

Why do we need to know how to calculate resultant force? (2)

Answer 26

Health eg Podiatry Sport

Question 27

Why do we need to know how to calculate resultant force in sport? (3)

Answer 27

improve running efficiency monitoring power reducing sport injuries