Introduction to the Work-Energy Principle

Practice flashcards covering definitions, formulas, and problem-solving steps for the work-energy principle.

How is work calculated?

Work is calculated as the product of the magnitude of a force times the displacement times the cosine of the angle between them.

What type of quantity is work, and what are its units?

Work is a scalar quantity, and its units are Newton meters, which are equivalent to joules.

What is net work equivalent to in terms of net force and displacement?

Net work is equivalent to the net force times the displacement times the cosine of the angle between them.

According to Newton's second law, what is net force equal to?

Net force is equal to mass times acceleration.

How is the kinematics equation adapted from one dimension into two dimensions?

By inserting the multiplication by the cosine of the angle between the acceleration and the displacement.

Why can the kinematics equation used in this derivation only be solved for speed rather than the direction of velocity?

Because the equation is in scalar form.

What is kinetic energy, and what is its mathematical expression?

Kinetic energy is the energy of motion, expressed by the formula $\frac{1}{2} m v^2$.

What type of quantity is kinetic energy, and what are its units?

Kinetic energy is a scalar quantity with units of joules.

What is the shorthand statement of the work-energy principle?

Net work is equal to the change in kinetic energy.

What three pieces of information are needed to solve work problems?

Information about the forces, the displacement, and the angles.

What is the first step in setting up a work problem, and what should be noted alongside it?

Start with a free body diagram and note the direction of the displacement on the side.

Why is the displacement value the same for each force in the forces, displacement, and angles table?

Because it is the same one object.

How much work is produced by forces that act perpendicular to the displacement?

Forces acting perpendicular to the displacement produce no work.

How is net work calculated from the individual work done by each force?

Net work is the algebraic sum of all the work done on the object.