Biomechanics

Question 1

What is Newton’s first Law of Motion?

Answer 1

Inertia - A body will remain in a state of rest or uniform velocity unless acted upon by an external or unbalanced force

Question 2

What is Newton’s Second Law of Motion?

Answer 2

Acceleration - The acceleration (or rate of change in momentum) of a body is proportional to the size of the force applied and takes place in the direction of which the force acts

Question 3

What is Newton’s Third Law of Motion?

Answer 3

Reaction - For every action there is an equal and opposite reaction. The reaction force is equal in size and opposite in direction to to the action force

Question 4

What are the 4 external forces that may act on motion?

Answer 4

1. Weight - Acts downwards from the centre of mass
2. Reaction - Acts upwards from the points of contact with the ground
3. Friction - Opposes the sliding motion of one surface across another
4. Air Resistance - Acts against the direction of motion, opposing the movement of the boy through air

Question 5

Define the Centre of Mass

Answer 5

The point at which a body is balanced in all directions and from which weight appears to act

Question 6

What 2 factors effect the centre of mass?

Answer 6

1. Shape - irregularly shaped bodies or bodies that are changing shape do not have a fixed centre of mass, because the centre of mass must be at a point where the body is balance in all directions
2. Density of different pats of the body

Question 7

Define Friction

Answer 7

The force opposing the sliding motion of one surface across another

Question 8

What factors affect friction?

Answer 8

Characteristics of both surfaces involved ie sole of a shoe on the playing surface, Weight/normal ground reaction force and Temperature ie heated tyres increase friction

Question 9

Define Air Resistance?

Answer 9

The force acting to oppose the motion of a body through air

Question 10

What factors affect Air resistance?

Answer 10

Velocity, frontal cross-sectional area, streamlining + shape and surface characteristics

Question 11

Define Stability

Answer 11

A measure of how easily a body is moved from one position of equilibrium or balance

Question 12

Define A Line of Gravity

Answer 12

An imaginary line extending vertically downward tot he ground from the centre of mass

Question 13

Define the base of support

Answer 13

The area enclosed by the points of contact with the ground

Question 14

What factors would contribute to greater stability?

Answer 14

Large bass support, Low centre of mass, Line of Gravity in line with the middle of the base support and a Large Mass

Question 15

What happens when 2 or more forces act?

Answer 15

If they act in the same direction, their effect is combined. If they act in opposition to each other, they have a cancelling effect

Question 16

Define a balanced force

Answer 16

When 2 or more forces acting on the same body are equal in size but opposite in direction all forces cancel out

Question 17

Define an unbalanced force

Answer 17

When 2 or more forces acting on a body do NOT cancel out this means a NET force acts

Question 18

Define a Net force

Answer 18

The overall force acting on a body hen all forces are considered - also known as the resultant force