Introduction to Mechanical Energy with Friction

The video tutorial covers the conservation of mechanical energy, focusing on when it is applicable, particularly in the absence of work done by friction or applied force. It explains how to solve problems involving work done by friction, detailing the equation and the significance of the angle between force and displacement. The direction of the force of friction is discussed, emphasizing its opposition to sliding motion. Special cases where friction aligns with displacement are highlighted, such as a hockey puck on a moving block. Finally, the tutorial explains that conservation of mechanical energy is a special case of the work due to friction equation.

When can the conservation of mechanical energy equation be used?

• When mechanical energy is not conserved

• When there is work done by applied forces

• When there is no work done by friction or applied forces

• When there is work done by friction

What is the equation for work done by friction?

• Force of friction times velocity times cosine of the angle

• Force of friction times displacement times cosine of the angle

• Force of friction times time times cosine of the angle

• Force of friction times displacement times sine of the angle

What does a change in mechanical energy represent?

• Initial mechanical energy minus final mechanical energy

• Final mechanical energy minus initial mechanical energy

• The sum of initial and final mechanical energy

• The product of initial and final mechanical energy

What is the typical angle between the force of friction and displacement?

• 360 degrees

• 180 degrees

• 90 degrees

• 0 degrees

In what situation can the force of friction be in the same direction as the object's motion?

• When the object is stationary

• When the object is moving uphill

• When the object is moving in a vacuum

• When a hockey puck is accelerated on a moving block