Work – in the physics sense of the word

Work – in the physics sense of the word

Work – in the physics sense of the word Work is force times distance (assuming the force is parallel to the displacement)

Work – in the physics sense of the word Units: 1 N x 1 m = 1 N·m = 1 J (Joule)

Work – in the physics sense of the word Units: 1 N x 1 m = 1 N·m = 1 J (Joule)

An intern pushes an 87 kg patient on an 18 kg gurney, producing an acceleration of 0.55 m/s2. (a) How much work does the intern do in pushing the patient and gurney through a distance of 1.9 m? Ignore friction.

An intern pushes an 87 kg patient on an 18 kg gurney, producing an acceleration of 0.55 m/s2. (a) How much work does the intern do in pushing the patient and gurney through a distance of 1.9 m? Ignore friction. (b) How far must the intern push the gurney to do 140 J of work?

What if the force acts at an angle to the displacement?

What if the force acts at an angle to the displacement?

In a gravity escape system, an enclosed lifeboat on a large ship is deployed by letting it slide down a ramp and then continue in free fall to the water below. Suppose a 4970 kg lifeboat slides a distance of 5.00 m on a ramp, dropping through a vertical distance of 2.50 m. How much work does gravity do on the boat while it’s on the ramp?

Work can be negative

Three forces act on a car coasting down a hill. Does each force do positive, negative, or zero work on the car?

The Work-Kinetic Energy Theorem Derivation…

Kinetic energy is sometimes called the “energy of motion” The Work-Kinetic Energy Theorem Kinetic Energy: Kinetic energy is sometimes called the “energy of motion”

Kinetic energy is sometimes called the “energy of motion” The Work-Kinetic Energy Theorem Kinetic Energy: Kinetic energy is sometimes called the “energy of motion” Units?

The Work-Kinetic Energy Theorem Kinetic energy is sometimes called the “energy of motion” Units? NOTE: K is never negative.

A hockey puck with mass m sliding on ice with speed v has kinetic energy K. What is its kinetic energy if we double its mass, keeping the speed at v? A) K B) 2K C) 3K D) 4K E) 5K

A hockey puck with mass m sliding on ice with speed v has kinetic energy K. What is its kinetic energy if we double its speed, keeping the mass at m? A) K B) 2K C) 3K D) 4K E) 5K

The Work-Kinetic Energy Theorem The net work done on an object is the change in its kinetic energy

When a father takes his son for a run in his stroller, he exerts a force of 35.0 N at an angle of 32.0º below the horizontal on the stroller. He exerts this force on the stroller over a distance of 2.75 m. If the initial speed of the stroller was 0.65 m/s, what is the final velocity?