Forces, Mechanics and Biomechanics

Question 1

Define speed. What is it measuring? What is the S.I unit of speed? Is it a scalar or vector quantity?

Answer 1

It is a measurement of the distance an object travels over time, the S.I unit is m/s and it is a scalar quantity (no direction)

Question 2

Define velocity. What is it measuring? What is the S.I unit of velocity? Is it a scalar or vector quantity?

Answer 2

It is a measurement of the distance an object travels over time in a specified direction, the S.I unit is m/s and it is a vector quantity (direction is included)

Question 3

Define mass. What is it measuring? What is the S.I unit of mass? Is it a scalar or vector quantity?

Answer 3

It is a measurement of the quantity of matter in something, the S.I unit is kg and it is a scalar quantity (no direction)

Question 4

Define weight. What is it measuring? What is the S.I unit of weight? Is it a scalar or vector quantity?

Answer 4

It is the downwards force an object exerts as a result of its mass and gravity acting upon it, the S.I unit is Newtons and it is a vector quantity (direction is included)

Question 5

Define acceleration. What is it measuring? What is the S.I unit of acceleration? Is it a scalar or vector quantity?

Answer 5

It is the change in velocity over time, the S.I unit is m/s^2 and it is a vector quantity (direction is included)

Question 6

What is full community ambulation?

Answer 6

The speed a person should be able to walk to safely navigate around the community (greater than 0.8m/s)

Question 7

What is limited community ambulation?

Answer 7

The range of speed a person walks if they may have some trouble navigating safely around the community e.g. crossing pedestrian crossings fast enough (0.8-0.4 m/s)

Question 8

What is household ambulation?

Answer 8

The speed a person walks if they are unable to safely navigate around the community (less than 0.4m/s)

Question 9

In the absence of friction, what will the acceleration of a 1kg object be under 1N of force?

Answer 9

1 m/s^2

Question 10

How much force can falling over onto your hip generate?

Answer 10

4000N (depending on person)

Question 11

How much force would it require to fracture an osteoporotic hip in a fall?

Answer 11

2000N (depending on hip and fall)

Question 12

What is friction?

Answer 12

The force that resists the movement of two objects moving in different directions while in contact/moving over each other.

Question 13

What are the functions of articular cartilage?

Answer 13

Shock absorption and smooth joint movement

Question 14

The lack of articular cartilage in a joint due to wear and tear is known as what?

Answer 14

Osteoarthritis, leading to pain and instability

Question 15

What is Newton’s first law of motion?

Answer 15

Every object in a state of uniform motion tends to remain in that state until an external force is applied to it

Question 16

What is Newton’s second law of motion?

Answer 16

The relationship between an object’s mass (m) and it’s acceleration (a) and the applied force (F) is F=ma, where the direction of the force and acceleration vectors are the same

Question 17

What is Newton’s third law of motion?

Answer 17

With every action, there is an equal and opposite reaction

Question 18

What is an object’s centre of gravity?

Answer 18

The equivalent point within an object at which the total weight of that object acts

Question 19

What is an object’s base of support?

Answer 19

The area beneath an object or person that includes every point of contact that the object or person makes with the supporting surface

Question 20

What are the common properties between all types of levers?

Answer 20

All levers involve a fulcrum, an effort force at a certain distance from the fulcrum and a load force at a certain distance from the fulcrum

Question 21

What are the relative positions of the effort and load forces with relation to the fulcrum in a first order lever? What is an example of this form of lever?

Answer 21

The effort and load forces are on either side of the fulcrum like a seesaw

Question 22

What are the relative positions of the effort and load forces with relation to the fulcrum in a second order lever? What is an example of this form of lever?

Answer 22

The load force is between the effort force and the fulcrum along the lever arm like a wheelbarrow or a foot pushing off the ground in a step

• Fulcrum = Metatarsals/toes
• Effort = Force of calf contraction via Achilles tendon
• Load = Body weight through shin bone and ankle joint

Question 23

What are the relative positions of the effort and load forces with relation to the fulcrum in a third order lever? What is an example of this form of lever?

Answer 23

The effort force is between the load force and the fulcrum along the lever arm like a bicep

• Fulcrum = Elbow
• Effort = Bicep
• Load = Forearm, Hand and Whatever’s being carried