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Question
Which statement best describes work?(1 point)
Responses
Work is done whenever a force acts on an object.
Work is done whenever a force acts on an object.
Work is done when an object continues in motion without a push.
Work is done when an object continues in motion without a push.
Work is done whenever an object is held in place by multiple forces.
Work is done whenever an object is held in place by multiple forces.
Work is done when a force causes an object to move.
Work is done when a force causes an object to move.
A shovel performs several different functions. One of these is that it gives mechanical advantage as a lever. When does it act like a lever? (1 point)
Responses
when the soil is lifted with the dirt at the end of the shovel and a lifting force at the handle
when the soil is lifted with the dirt at the end of the shovel and a lifting force at the handle
when you step up onto the shovel with both feet to use your body weight
when you step up onto the shovel with both feet to use your body weight
when the shovel is in the dirt and you push down against the end of the shovel, making it pivot
when the shovel is in the dirt and you push down against the end of the shovel, making it pivot
when you push the shovel downward into the dirt and a small force allows you to push down into the dirt easily
when the shovel is in the dirt and you push down against the end of the shovel, making it pivot
A person uses a screwdriver as a lever to open a can of paint. Where is the fulcrum in this situation?(1 point)
Responses
the point where the person holds onto the can to keep it in place
the point where the person holds onto the can to keep it in place
the point where the end of the screwdriver lifts up the lid of the can
the point where the end of the screwdriver lifts up the lid of the can
the point where the person pushes down on the screwdriver
the point where the person pushes down on the screwdriver
the point where the screwdriver touches the rim of the can
the point where the screwdriver touches the rim of the can
the point where the screwdriver touches the rim of the can
Which car has the greatest efficiency?(1 point)
Responses
a 1,200 kg car that travels 20 km per liter of fuel
a 1,200 kg car that travels 20 km per liter of fuel
a 1,200 kg car that travels 15 km per liter of fuel
a 1,200 kg car that travels 15 km per liter of fuel
a 900 kg car that travels 20 km per liter of fuel
a 900 kg car that travels 20 km per liter of fuel
a 900 kg car that travels 15 km per liter of fuel
a 1,200 kg car that travels 20 km per liter of fuel
Why are incandescent light bulbs considered to be lower efficiency than LED bulbs?(1 point)
Responses
A greater amount of energy is required for the same light output from the LED bulb.
A greater amount of energy is required for the same light output from the LED bulb.
A smaller amount of energy is wasted by the incandescent bulb.
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 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 percentage of the energy output of the incandescent bulb goes toward heat.
What can be done to improve the efficiency of a ramp?(1 point)
Responses
Add a rough surface.
Add a rough surface.
Insulate the surface with foam.
Insulate the surface with foam.
Smooth the surface.
Smooth the surface.
Make it shorter and steeper.