Mechanical Analysis Exam 3 - In Class Review

If a person is moving in the negative horizontal direction, in what direction will friction act?

positive horizontal direction

What variable is the product of average force and the time over which it is applied?

Impulse, which is equal to change in momentum

Describe a hard landing

a large amount of force applied over a shorter time period; very little flexion in hips, knees, and ankles upon landing

A person weighs 500 N, and they land with 1,500 N of force. What is their force normalized to multiples of body weight?

3.0 BW

A person is running, and their braking force/impulse is greater than their propulsive force/ impulse. What will happen to their running velocity?

It will decrease

While the amount of peak force is important, what other variable related to force is just as or even more important?

Rate of force development

The perpendicular distance from the line of action to the axis of rotation is the

Moment arm

The distance from the point of force application to the axis of rotation is the

lever arm

If you are using the lever arm to calculate torque, you should multiply it by what?

perpendicular component of the force

If you are using the moment arm to calculate torque, you should multiply it by what?

force

If torque remains constant, and the moment of inertia increases, what happens to angular acceleration?

it decreases

1st class lever arrangement

RAF or FAR

2nd class lever arrangement

ARF or FRA

3rd class lever arrangement

AFR or RFA

Which function of a simple machine does a 1st class lever favor?

potentially all four functions

Which function of a simple machine does a 2nd class lever favor?

Force production

Which function of a simple machine does a 3rd class lever favor?

speed and range of motion

What class of lever is knee extension

3rd class

What class of lever is elbow extension

1st class

What class of lever is cervical/neck extension

1st class

What class of lever is a toe raise

2nd class

What is the angular equivalent of newton’s 1st law?

angular momentum will not change without the application of an outside torque

What is the angular equivalent of newton’s 2nd law?

T = Ia

What is the angular equivalent of newton’s 3rd law?

for every torque, there is an equal and opposite reaction torque

What is the product of torque and the time over which torque is applied?

Angular impulse, product is equal to angular momentum

In order to maintain balance, the ______ must remain within the ______

center of pressure, base of support

Energy due to motion is known as

kinetic energy

Energy due to position is known as

potential energy

A person is standing still on a 10m high diving platform, what type of energy do they have?

Potential energy

A person is running off a 10m high diving platform, what type of energy do they have?

both kinetic and potential energy

A person is performing a vertical jump. what is the relationship between potential and kinetic energy on the way up?

kinetic energy is being transformed into potential energy

At the apex?

total energy equals potential energy, kinetic energy is zero

On the way down?

potential energy is being transformed into kinetic energy

Work is the product of what two variables?

Force and displacement

What type of work and muscle action is being done when force and displacement are in opposite directions?

negative work, eccentric muscle action

What type of work and muscle action is being done when a large amount of force is applied, but there is no displacement?

No work, isometric muscle action

What type of work and muscle action is being done when force and displacement are in the same direction?

positive work, concentric muscle action

If person A requires more energy to complete the same task as person B, which person is more economical?

Person B

What typically happens to efficiency as a person ages, or after they sustain an injury or neurological damage like a stroke?

they become less efficient

In what form of locomotion is kinetic energy transformed into potential energy, and potential energy to kinetic energy?

Walking

Which form of locomotion can be described as a mass on top of a spring?

Running

What is the difference between work and power?

power has a time component and work does not

What is the equation for power?

P=W/t, P=Fv