Week 11 - Defining Work

Question 1

Mechanical work and equation

Answer 1

Force applied to displace a body/object

Work (W) = Force (F) * displacement (d)

W = Fd

Question 2

Mechanical power

Answer 2

Rate of work production

Question 3

Mechanical Energy

Answer 3

Capacity to do work

2 types

kinetic, potential (gravitational, strain)

Question 4

Positive work

Answer 4

Force and displacement in the same direction

e.g. lifting an object up

Concentric muscle contraction

Question 5

Negative work

Answer 5

Force displacement in opposite direction

e.g. putting an object down

Eccentric muscle contraction

Question 6

No work in relation to mechanical work

Answer 6

Force applied but object does not move

e.g. holding an object still

Isometric muscle contraction

Question 7

What type of work is this and why?

Answer 7

Positive as the muscles are contracting and pushing the weight in the same direction

Question 8

What type of work is this and why?

Answer 8

Negative work as the muscles are eccentrically contracting and the force is moving in the opposite direction

Question 9

What type of work is this and why?

Answer 9

No work, as it is an isometric contraction and no movement of the object is occurring

Question 10

How much mechanical work is performed when 100 N of force applied vertically is used to lift a barbell 2 metres off the ground?

Answer 10

W = Fd

100N x 2m

= 200 Nm of work