4.3 - Biomechanics

Question 1

What are scalar quantities?

Answer 1

Only a magnitude ex. body mass and height, speed

Question 2

What are vector quantities?

Answer 2

Direction and a magnitude ex. acceleration, velocity, drag, momentum

Question 3

What does force mean and what’s it’s equation?

Answer 3

The mechanical interaction that goes on between two objects - mass x acceleration

Question 4

What does speed mean and what’s it’s equation?

Answer 4

The rate at which someone or something is able to move or operate at - distance/time

Question 5

What does acceleration mean and what’s it’s equation?

Answer 5

The rate of change of velocity - change in velocity/time

Question 6

What does velocity mean and what’s it’s equation?

Answer 6

The speed of something in a given direction - displacement change/time

Question 7

What does displacement mean?

Answer 7

The direct distance from a starting point

Question 8

What does momentum mean and what’s it’s equation?

Answer 8

The quantity of motion of a moving body, measured as a product of its mass and velocity - mass x velocity - mass in motion

Question 9

What does impulse mean and what’s it’s equation?

Answer 9

Force felt during s collision multiplied by the duration of the collision - force x time - it’s the increase or decrease of an object’s momentum

Question 10

What is Newton’s first law of motion?

Answer 10

“An object will remain at rest or continue with constant velocity unless acted on by an unbalanced force.”

Question 11

What is Newton’s second law of motion?

Answer 11

“The acceleration is proportional to, and in the same direction as, the unbalanced force applied to it” - force = mass x acceleration - relates to change in motion

Question 12

What is Newton’s third law of motion?

Answer 12

When one body/object applies a force to another, the second body/object will apply a force equal in size but opposite in direction to the first body/object. - action = reaction

Question 13

Explain the conservation of momentum

Answer 13

Conserved = constant
During a collision between two people the total momentum of the two people before the collision is equal to the total momentum of the two people after the collision. The momentum lost by person 1 is equal to the momentum gained by person 2.

Question 14

Define the term centre of mass

Answer 14

The centre of mass is the point in which the mass of the body is evenly distributed

Question 15

What is a lever?

Answer 15

Rigid structures hinged at one point (fulcrum) to which forces are applied to two other points (effort and load)

Question 16

Distinguish between first, second, and third class levers

Answer 16

1st class has the fulcrum in the middle
2nd class has the load in the middle
3rd class has the effort or applied force in the middle

Question 17

What is the equation for angular momentum?

Answer 17

L (angular momentum - something rotating around fixed axis) = I (moment of inertia) x W (angular velocity)

Question 18

What is torque?

Answer 18

The ability of a force to rotate a body about an axis (T = force x distance)

Question 19

What does the size of torque rely on?

Answer 19

the size of the force, the direction of the force, how far it is applied from the axis of rotation

Question 20

What is moment of inertia?

Answer 20

A body’s resistance to a change in its’ state of rotational motion - how difficult it is for a body to rotate about an axis

Question 21

What does the moment of inertia depend on?

Answer 21

Mass of the object
Mass distribution around the axis - more mass further away from the axis gives a greater moment of inertia and it will be more difficult to rotate

Question 22

What are the three factors that effect the projectile motion of an object?

Answer 22

Angle of release - how high and how far it will reach
Height of release - thrown from a height will mean the maximum height and maximum range achieved will be greater
Speed of release - how high and how far it will reach

Question 23

Summarise the Bernoulli principle

Answer 23

The faster a gas or fluid is flowing, the lower it’s air pressure (high speed = low pressure - vise virsa)
Lift (magnus effect) acts perpendicular to the direction of motion
High pressure beneath the object pushes up to cause lift