W6 Mechanical (Work, Power & Energy)

Question 1

• What is the formula for mechanical work?

Answer 1

Work (J) = Force (N) x Displacement (m)

Question 2

• Whats the definition of mechanical work?

Answer 2

• Mechanical work is equal to the product of the force applied to an object & the displacement of the object while the force is being applied.
• 1J = 1Nm
• E.g. during the pull stage of a snatch exercise. The total system work is the displacement multiplied by the resultant force

Question 3

What’s the formula for Total System Work?

Answer 3

Total System Work = ∑ (Sum of all) Forces x Displacement

Question 4

• What is Positive Work?

- What is Negative Work?

Answer 4

Positive Work = Work occurs when the displacement is in the same direction as the force of interest
Negative Work = Work occurs when the displacement is in the opposite direction as the force of interest

Question 5

• Will you see work occurring when someone is not moving?

Answer 5

• No, there will be no work if there is no movement.

Question 6

• What’s the definition of Mechanical Power?

Answer 6

• Mechanical Power is the rate at which work is performed.

- It differs from the work because it takes into account the speed of a movement

Question 7

What is the formula for Mechanical Power?

Answer 7

Power = Work / Time

Question 8

What is the definition of Mechanical Energy?

Answer 8

• Mechanical energy is the capacity of a system to do work
• We can also define work as being equal to the change in energy
• Both have joules (J)

Question 9

What is the definition of Kinetic Energy?

Answer 9

• Energy resulting from motion

Question 10

What is the definition of Gravitational Potential Energy?

Answer 10

• It is energy objects possesses because of its in the gravitational field.
• We usually think of this as an objects height above the ground

Question 11

What is the definition of Strain Energy?

Answer 11

• An object that is deformed by force may also store potential energy
• Strain Energy depends on the stiffness (k) of an object and amount of deformation that occurs

Question 12

Within a closed system can energy be created or destroyed?

Answer 12

• No, energy cannot be created or destroyed but can be conserved
• It can be transferred

Question 13

What three types of energy are included in Total Mechanical Energy?

Answer 13

1. Potential Energy
2. Kinetic Energy
3. Strain Energy