What is the formula for power? Bellwork 10.25.17 What is the formula for power? If time doubles, how does that affect power?

Incline Plane An inclined plane is a sloping surface. The material an inclined plane is made from can change the efficiency of the inclined plane. The length of an inclined plane can change the efficiency of the inclined plane. Wedges are inclined planes that move; like a knife. How sharp a wedge is can change the efficiency of the wedge.

Inclined Plane An inclined plane is a sloping surface (like a ramp) that reduces the amount of force required to move an object/load. An inclined plane can be designed to reduce the force needed to lift an object/load in two ways:

Increase the length of a ramp in this example, the same amount of work is done as the distance of the effort force is increased but the object/load still is moved to the same height Same height but distance is increased Same height but distance is decreased

Decrease the height of the ramp In this example, less work is done because the object/load is not moved to the same height By increasing the distance the effort force moves (length of the ramp) relative to the distance the object/load is moved (height of the ramp); an inclined plane can reduce the effort force needed.

Mechanical Efficiency Mechanical efficiency measures how well a machine converts input energy, work, and power into output energy, work, and power.

The efficiency of an ideal machine is 100% because the input work equals the output work. However, real machines do not achieve an efficiency of 100% because heat may be lost from the system do to the friction between moving parts.

An important way to improve the efficiency of a machine is to reduce friction. For example, a pulley with a rope running over a wheel is more efficient than a pulley where the rope only runs over a bar. The spinning wheel in the first example reduces friction and makes the machine more efficient.

Exit Ticket 10.25.17 What other simple machine is an inclined plane? True/False: Mechanical efficiency measures how well a machine converts input energy, work, and power into output energy, work, and power. What did you learn today?