Chapter 12 Flashcards
Multiple pulleys put together in a single unit
Block and tackle
Which of the following is not a simple machine?
A pair of scissors
A dropped racquetball will not return to it’s original position because
Some of the mechanical energy is converted to nontechnical energy
The sum of an objects kinetic and potential energies
Mechanical energy
A lever it pulley connected to a shaft
Wheel and axle
The energy due to motion
Kinetic energy
What are the units of work?
All of these
An inclined plane
Changes both the magnitude and the direction of the force
A ramp is a simple inclined plane the allows one to apply an input force _____ the output force
Less than
A ramp is a _______ that decreases the force required to move an object while increasing the distance the object travels
Machine
Which of the following statements is NOT true?
If the kinetic energy of an object decreases, the nonmechanical energy will decrease
At the top of its arc, a thrown ball has _______ potential energy
Maximum
Which of the following is an example of a wheel and axle?
A screwdriver
An example of a second-class lever
Wheelbarrow
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 is called
Work
What is the mechanical advantage of a single, fixed pulley?
1
The law of conservation of energy states that
Energy can neither be created nor destroyed
Gravitational potential energy depends on the
All of these
Which of the following is an example of a third-class lever?
A hand-held boat paddle
A boy exerts an average force if 50 N when he lifts a box 4 meters. How much work does he do?
200J
The energy of an object due to its position,shape, or condition
Potential energy
Energy that lies at the level of atoms and that does not affect motion on a large scale
Nonmechanical energy
A system that receives energy from external sources is called
Open
What is the mechanical advantage of a ramp that is 16 meters long and 2 meters high?
8
Levers are divided into_______ classes based o the location of the fulcrum and of the input and output forces
Three
Which of the following is an example of mechanical energy?
Potential energy
______ is a measure of the ability to do work
Energy
A wedge is a modified
Inclined plane
Which of the following is not in the inclined plane family?
A wheel and axle
How much power is required to do 200 J of work in 5 S?
40 W
Mechanical energy can change to nonmechanical energy as a result of
Air resistance and friction
______ is defined as the rate at which work is done
Power
A boy pushes on a parked car with a force of 200 N. the car does not move. How much work does the boy do on the car?
Zero
Calculate the mechanical advantage of a wrench that allows you to move a bolt 0.1 M by moving the handle 0.3 M
3
A pair of tweezers is
A compound machine made of two third-class levers
As a dropped penny falls toward the ground ______ energy is converted to _______ energy
Potential, kinetic
When a pitcher throws a softball to a catcher, the vibration of the individual atoms that make up the softball is considered ______ energy while the motion of the ball toward the catcher is considered ____ energy
Nonmechanical, mechanical
What are the units of power?
All of these
A man pushes a crate along a factory floor by exerting a force of 100 N. if the crate moves a distance if 8.0 M, how much work does the man perform?
800 J
What are the two families of simple machines?
Inclined plane and lever
An inclined plane wrapped around a cylinder
Screw
Which of the following statements about work and energy is NOT true?
Work and energy are always equal
The primary source of the suns energy is
Nuclear fusion
A machine is a device that
Can multiply and change the direction of an input force
A first-class lever has the
Fulcrum in the middle
________ is the ratio of useful work output to work input
Efficiency
The kind of energy associated with atomic bonds is
Chemical energy
Lifting a car using a car jack is easier because it requires
Less force
