Physical Science-Chapter 5
In a wheel and axle, which of the following usually exerts the output force? A. the axle B. the wheel c. the fulcrum d. the input arm
A. the axle
in an ideal machine which of the following is true? A. work input is equal to work output B. work input is greater than work output C. work input is less than work putput D. The IMA is always equal to one
A. work input is equal to work output
Which one of these is not done by a machine? A. Multiply force B. Multiply Energy C. Change direction of a force D. Work
B. Multiply Energy
Using the scientific definition which of the following is true of work. A. it is difficult B. it involves levers. C. It involves a transfer of energy D. It is done with a machine.
C. It involves a transfer of energy
what happens to energy when work is done?
Energy is transferred between what is doing the work to what ks moved.
Under certain conditions it is possible to get more work out of a machine tha you put into it.
FALSE
When a machine is used to do work, the force is applied by the machine is called the effort force.
FALSE
Friction changes the useful work of a machine into MECHANICAL energy.
FALSE. Friction changes the useful work of a machine into THERMAL energy
ACTUAL mechanical advantage is determined with the equation MA= F,r F,e
FALSE. Ideal Mechanicsl advantage is determined with that equation
Power is done over A DISTANCE.
FALSE. Power is work done over time.
How could you increase the IMA of an inclined plane?
Increase its length
the amount by which a machine multiplies an effort force is called the.......
Mechanical advantage
What term indicates the number of times a machine multiplies the input force?
Mechanicl advntage
How are work,time, and power related?
Power is work divided by time. P=_W_ t
Reducing friction increases the IDEAL MECHANICAL ADVANTAGE of a machine.
Reducing friction increases the EFFICIENCY of a machine.
Examples of all three claases of levers are found in the human body.
TRUE
In order for work to be done on an object, the object must move.
TRUE
Some machines dont multiply the force that is applied to them.
TRUE
The longer arm of a lever with a mechanical advantage greater than 1 is the EFFORT arm.
TRUE
power
amount of work done, or the amount of energy transferred, divided by the time required to do the work or transfer the energy; measured in watts.
which of the following increases as the efficency of a machine increases? A. Work input B. work output C. Friction D. IMA
b. work output
An arragement of pulleys designed to reduce the effort force is called a
block and tackle
When two or more simple machines work together they are called a(n).....
compound machine
machine
device that makes doing work easier by increasing the force applied to an object, changing the direction of an applied force, or increasing the distance over which a force can be applied.
________ is a measure of how much of the work put inot a machine is canged into useful work put out by the machine.
efficiency
two simple machines that are part of a bicycle are a(n)
gear and a wheel and axle
A slanted surface used to raise an object is a(n)
inclined plane
nA winding mountain road is an example of a(n)....
inclined plane
A lever with a mechanical advantage greater than 1 is ised to
increase force
what would happen to the mechanical advantage of a doorknob if the radius was 4.8 cm and was doubled?
it would be multiplied by 2
When a machine is used to perform a task , the work output is always .................. than work input...
less
a bar that is free to pivot about a fixed point is a
lever
If a weight lifter is holding barbells above his head, what does he have to do to perform work?
lower barbells
simple machine
machine that does work with only one movement - lever, pulley, wheel and axle, inclined plane, screw, and wedge
compound machine
machine that is a combination of two or more simple machines
unlike a fixed pulley a movable pulley___________ the effort force
multiplies
The rate at which work is done is called .....
power
efficiency
ratio of the output work done by the machine to the input work done on the machine expressed as a percentage
mechanical advantag
ration of the output force exerted by a machine to th input force applied to th machine.
To calculate mechanical advantage you divide the...................force by the effort force
resistance
An inclined plane wrapped around a cylindrical post is a
screw
what type of simple machine is your foot when you stand on your toes?
second-class lever
A device that does work with only one movement and changes the size or direction of a force is a(n)
simple machine
lever
simple machine comsisting of a bar free to pivot about a fixed point called the fulcrum.
pulley
simple machine that consists of a shaft or axle attached to the center of a larger wheel, so that the shaft and the wheel rotate together.
screw
simple machine that consists of an inclined plane wrapped in spiral around a cylindrical post.
wedge
simple machine that is an inclined plane with one or two sloping sides
inclined plane
simple machine twt consists of a sloping surface, such as a ramp, that reduces the amount of force needed to lift something by increasing the distance over which the force is applied
How many types of simple machines exist
six
output force
the force applied BY the machine
Input force
the force thqt is applied TO the machine.
work
transfer of energy that occurs when a force makes an object move; measured in joules.
the unit of power is the....
watt
three of the following simple machines are basically the same. the one that does NOT belong with the group is the
wedge
doorknobs and faucet handles are exapmles of a simple machine called a ___________
wheel and axle
A machine that changes only the direction of a force has a mechanical advantage of ....
1
