Work
The definition for work
Exerting a force through a distance causing displacement in the direction of the force.
The definition of power...
the rate at which work is done, or the rate at which energy is transfered, or work divided by time
The definition of energy...
the ability to do work or cause change
The law of conservation of energy states that energy cannot be
created or destroyed
Athletes with a combined mass of 200 kg are doing wall sits for 90 s. How much work are they doing?
zero
The SI unit of power is...
Watt
The energy stored in a stretched or compressed spring
elastic potential
The conservation of mechanical energy states
the total kinetic & potential energy remains constant in a closed system
If the sign of work is negative, as in friction doing work to stop a moving bicycle, the direction of the force is...
opposite the motion or opposite the displacement
746 Watts equals 1...
horsepower
Gravitational potential energy is measured from a
reference level
When friction is present, some of the kinetc energy...
changes to thermal energy
Describe a situation in which a force is exerted on an object, but no work is done.
the force is not in the same direction as the displacement, or the object doesn't move
James Watt determined a value for horsepower because he was trying to sell...
steam engines
Use one simple sentence to explain how change in energy, time, and power are related.
power is equal to change in energy divided by time, or power is the rate at which energy changes
How much kinetic energy does a 50. kg runner have moving at 10. m/s?
2500 J
The work-energy theorem states...
Work done on an object is equal to the change in energy of the object
Describe how someone running stairs could utilize/generate more power.
run faster or carry weight
The difference between kinetic and potential energy is
kinetic is due to motion and potential is stored due to position/condition
If an object is positioned 5.0 m and moves down a fricionless slide. At the bottom, the speed is
9.9 m/s