Question

A) Which car has the greatest efficiency? (1 point)
a 1,200 kg car that travels 15 km per liter of fuel
a 1,200 kg car that travels 20 km per liter of fuel
a 900 kg car that travels 15 km per liter of fuel
a 900 kg car that travels 20 km per liter of fuel

A) Why are incandescent light bulbs considered to be lower efficiency than LED bulbs? (1 point)
A smaller amount of energy is wasted by the incandescent bulb.
A greater percentage of the energy output of the incandescent bulb goes toward heat.
A smaller percentage of the energy output of the LED bulb goes toward light.
A greater amount of energy is required for the same light output from the LED bulb.

A) What can be done to improve the efficiency of a ramp? (1 point)
Smooth the surface.
Add a rough surface.
Make it shorter and steeper.
Insulate the surface with foam.

A) What is the name of the fixed point about which a lever rotates? (1 point)
bar
pulley
groove
fulcrum

A) A pulley system is operating at only 50% efficiency. How could the efficiency be increased? (1 point)
by adding more pulleys to the system
by decreasing the amount of weight being lifted
by having a second person pulling on the rope
by reducing the friction on the pulleys

Answer 1

1) 900 kg car that travels 20 km per liter of fuel.
- It has the best fuel economy and the lowest mass of the 20 km/L options.

2) A greater percentage of the energy output of the incandescent bulb goes toward heat.
- Incandescents waste more energy as heat compared with LEDs.

3) Smooth the surface.
- Reducing friction increases ramp efficiency.

4) Fulcrum.

5) By reducing the friction on the pulleys.
- Less friction raises the mechanical efficiency of the system.