Vocabulary
Define Work
the transfer of energy to a body by the application of a force that causes the body to move in the direction of the force; it is equal to the product of the magnitude of the component of a force along the direction of displacement and the magnitude of the displacement
Joules (J)
A person lifts a 4.5 kg cement block a vertical distance of 1.2 m and then carries the block horizontally a distance of 7.3 m. Determine the work done by the person and by the force of gravity in this process
53 J,-53 J
Define the formula for Work
W=Fdcosθ
Define Kinetic Energy
the energy of an object that is due to the object's motion
Define the SI unit for Force
Newton (N)
When catching a baseball, a catcher’s glove moves by 10 cm along the line of motion of the ball. If the baseball exerts a force of 475 N on the glove, how much work is done by the ball?
47.5 J
Define the formula for the Work-Kinetic Energy Theorem
Wnet = ΔKE
Define Gravitational Potential Energy
the potential energy stored in the gravitational fields of interacting bodies
Define the SI unit for Displacement
Meter (M)
What is the kinetic energy of an automobile with mass of 1250 kg traveling at a speed of 11 m/s?
7.6×104J
Define the formula for Kinetic Energy
KE=1/2(ms2)
Define Work Kinetic Energy Theorem
the theorem that states that the change in kinetic energy of a moving particle is equal to the work done by all of the forces acting on the particle
Define the SI unit for Gravitational Potential Energy
Joules (J) per Kilogram (kg)
A child and sled with a combined mass of 50.0 kg slide down a frictionless hill that is 7.34 m high. If the sled starts from rest, what is the mechanical energy of the system, and what is the sled’s speed at the bottom of the hill?
3600 J; 12.0 m/s
Define the formula for Elastic Potential Energy
PEelastic=1/2(kx2)
Define Potential Energy
the energy that an object has because of the position, shape, or condition of the object
Define the SI unit for Power
Watt (W)
If an automobile engine delivers 50.0 hp of power, how much time will it take for the engine to do 6.40 × 105 J of work? (Hint: Note that one horse- power, 1 hp, is equal to 746 watts.)
17.2 s
Define the formula for Conservation of Mechanical Energy
MEI=MEF