Science Test; Machines
To which class of lever does each of the following machines belong: (i) fishing pole; (ii) wheelbarrow; (iii) bottle opener; (iv) pliers?
(i) is 3rd (ii) is 2nd (iii) is 2nd (iv) is 1st
An ideal machine would have an efficiency of
100%
The efficiency of an actual machine is always less than
100%
The mechanical advantage of a machine that changes only the direction of a force is
1
Which machine has the greatest ideal mechanical advantage?
5
The output work of a certain machine is 12,600 J. If the input work is 18,000 J, the efficiency is
70%
One example of a compound machine is a
Bicycle
A machine that utilizes two or more simple machine sis called a
Compound machine
Which of these is an example of a third-class lever
Fishing pole
True or false. The ideal mechanical advantage of a wheel and axle is the radius of the wheel TIMES the radius of the axle.
False; Divided by
True or false. JOULE is the rate at which work is done.
False; Power
True or false. A wheel and axle is a COMPOUND machine
False; Simple
The ideal mechanical advantage would equal the actual mechanical advantage if there were no losses due to
Friction
In machine 2, which letter represents the input force
G
In order to do work on an object, the force you exert must be
In the same direction as the object's motion
A ramp in a parking garage is an example of a simple machined called a(n)
Inclined Plane
The force applied to a machine is called the _____ force.
Input
How can a hockey stick be considered a machine?
It multiplies distance
Which body parts act as the fulcrums of levers?
Joints
A paint can opener acts as a simple machine called a
Lever
The wedge, screw, and lever are all
Simple Machones
The ideal mechanical advantage of a wheel and axle is equal to the
Radius of the wheel divided by the radius of the axle
A gardener pushes on the angled handle of a lawn mower, causing the mower to move forward across a lawn. The only portion of the gardener's force that does work on the lawn mower is the force in the _______ direction.
Same
A jar lid is an example of a simple machine called a
Screw
Which of these could be considered an inclined plane wrapped around a cylinder?
Screw
True or false. The force exerted by a machine is called the OUTPUT force
True
True or false. You do WORK on an object when you lift it off the floor onto a shelf.
True
A device that is twice as powerful as another can do ________ the amount of work in the same amount of time.
Twice
Power is measured in units called
Watts
A simple machine that might be thought of as an inclined plane that moves is a
Wedge
A screwdriver is a simple machine called a
Wheel and axle
The ideal mechanical advantage for an inclined plane is equal to the length of the incline divided by the
height of the incline
Most of the machines in your body consist of bones and muscles acting together as
levers
For work to be done on an object,
the object must move some distance as a result of a force.
