Work, Energy, Power Lecture Notes

A comprehensive set of flashcards covering key concepts of work, energy, and power as discussed in the lecture.

Which of the following are scalar quantities?

Work, kinetic energy, potential energy, and power.

What is the basic SI unit of measurement for mechanical work?

Joule (J).

What is the basic SI unit of measurement for gravitational potential energy?

Joule (J).

How is mechanical work defined?

The product of the net external force acting on an object and the displacement along the line of action of the force.

Kinetic energy is what?

The capacity of an object to do work based on its motion

An individual is using a seated knee extension exercise machine to strengthen their quadriceps. During the extension portion of the exercise, ____ work is performed because the _____.

Positive : quadriceps muscle force acts in the same direction as the joint movement

An individual is using a prone (laying on the stomach) knee flexion exercise machine to strengthen their hamstrings. During the extension portion of the exercise, _____ work is performed because the _____.

Negative: hamstrings muscle force acts in the opposite direction of the joint movement

During the raising phase (lifting the barbell off the ground) of a deadlift exercise, the hip ____ act ____ to _____ the hip joint.

extensors : concentrically : extend

During the lowering phase (moving from a standing upright position to a squat position) of a squat exercise, the knee ____ act ____ to control _____ of the knee joint.

extensors: eccentrically : flexion

If mechanical work is performed on an object that is in motion, the mechanical energy of the object _____.

may increase or decrease depending upon the direction of mechanical work with respect to the direction of motion of the object

If positive mechanical work is performed on an object that is in motion, the mechanical energy of the object _____.

will increase

If an individual performing a vertical jump wants to increase their vertical velocity at take-off, they could _____.

Increase the magnitude of the net vertical force and/or the displacement in the vertical direction while the force is acting.

An individual performs two drop landings from the exact same height above two different basketball floors. The first landing is onto a suspended basketball floor (hardwood suspended above the concrete/ground). The second landing is onto a traditional basketball floor (hardwood on the concrete/ground). The mechanical work performed on the individual to bring them to a stop would be ____ because the ____.

The same during both landings : change in mechanical energy would be the same

An individual performs two drop landings from the exact same height above two different basketball floors. The first landing is onto a suspended basketball floor (hardwood suspended above the concrete/ground). The second landing is onto a traditional basketball floor (hardwood on the concrete/ground). The net vertical force acting on the individual to bring them to a stop would be ____ because the ____.

Less during the first landing : displacement along the line of action of the force would be greater

A long jumper leaves the ground with 750 J of mechanical energy. At the vertical apex of the long jumper’s trajectory, their total mechanical energy will be _____.

750 J.

A long jumper leaves the ground with 750 J of mechanical energy. At the vertical apex of the long jumper’s trajectory, their vertical kinetic energy will be _____.

0 J.

What is the best mechanical indicator of the intensity of a physical task?

Power

Power is _____.

directly proportional to the mechanical work performed and inversely proportional to the time over which the work is performed

_____ influence(s) the ability of humans to produce and sustain power.

Muscle length, muscle shortening velocity, and task duration.

The primary factor influencing the ability of humans to sustain power is the ___

The metabolic system.

As the duration of a task (e.g. length of a cycle race) increases, the human body’s ability to sustain high average power output _____.

It decreases.

Potential energy is the capacity of an object to do work based on

displacement along the line of action