Chapters 10-11 Flashcards
A wheelbarrow is an example of a class ……. lever.
Class 2 lever
A pry bar is an example of a class ….. lever.
Class 1 lever
A fly swatter is an example of a class ….. lever.
Class 3 lever
A pair of scissors is an example of a class ….. lever.
Class 1 lever
The equation IMA =2(pie)r/p is used to find the IMA of a …..
Screw
For a simple machine, the ratio of output force to input force is …..
AMA
Actual mechanical advantage
For a simple machine, the ratio of input distance to output distance is …..
IMA
Ideal mechanical advantage
What is defined as the time rate of doing work?
Power
The SI unit for frequency is the ……
hertz (Hz).
A freely swinging mass hanging by a thin, massless connector is called a(n) …… pendulum.
Simple
An object that moves back and forth over the same path and completes every round trip in the same amount of time is in …… motion.
Oscillatory motion
The product of force and displacement is ……
Work
The SI unit of work is the …..
joule (J).
An object oscillating along a straight line caused by a restoring force proportional to its displacement is exhibiting ……
Simple harmonic motion
Any effort that produces motion is called …..
Work
A lever with the load and the input force on opposite sides of the pivot point is called a ….. class lever.
class 1 lever
The SI unit of power is the …..
watt (W).
The ….. mechanical advantage is what the mechanical advantage would be if there were no energy losses due to friction or other causes.
Ideal
The point at which a lever pivots is called the ……
Fulcrum
One horsepower is equal to ….. ft.(•)lb/s.
Ask me about this one
550
True/False
When a weight lifter lowers the weights, he is doing (positive) work.
Negative
A series of pulleys working in conjunction is called a (block and tackle).
True
The IMA of any simple machine will be (greater) in value than the machine’s AMA.
True
An object in uniform circular motion has a constant (velocity).
Speed
If a centripetal force is the action, a (normal) force is the reaction.
centrifugal
The (amplitude) of oscillation is the maximum displacement of an oscillation.
True
The (period) of oscillation is how many oscillations occur in a given time.
frequency
When you (double) the length of a pendulum, you also double the period of the pendulum.
quadruple
As the mass of a pendulum increases, the period (decreases).
Increases
As the driving frequency approaches the natural frequency of vibration, the amplitude of vibration (increases).
True
When the natural frequency of vibration is close to the driving frequency, the result is (simple harmonic motion).
resonance
Equations
Write the correct equation to:
Determine work when the force and motion are not along the same line of action.
W= Fd cos(-) theta
Equation for
The law of levers.
F(i)r(i)= F(o)r(o)
(i) input lever arm
(o) output lever arm
Equation for the centripetal acceleration of an object.
ac (centripetal acceleration) = v^2
———
r
Short answer
Define the three classes of levers by telling where their pivot point, output, and input are in relation to each other.
If the input force and output force are located on opposite sides of the fulcrum, this is a class one lever.
It is a class two lever if the output force (load) is between the fulcrum and the input force; and it is a class three lever if the input force is between the fulcrum and the load.
Write three of the four laws of a pendulum.
The period of the pendulum…
(1) depends on the square root of it length.
(2) is inversely dependent on the square root of the rate of acceleration due to gravity.
(3) does not depend on its mass.
Explain why major highway curves are banked.
Major highway curves are banked to protect motorists from flipping their cars. Banked curves help prevent vehicles from losing traction caused by centripetal force between the tires and the road.
Problems
Two children are holding onto opposite ends of a rope. The one on roller skates is being swung around in circles. If the moving child weighs 75 lb and he attains a constant speed of 12 ft/s, and if the rope is 10 ft long, how much tension is in the rope? Neglect friction.
F(centripetal)= m•v^2
———
r
As a boy pulls a sled carrying his sister, he exerts a force of 2.6 lb at an angle of 30 degrees with the ground. How much work does he do if he pulls her at constant speed for exactly one-half mile (2640 ft).
W=Fd cos(-) theta
1 J= 0.7376 ft•lb
5280 ft.= 1 mile= 1609 meters
1 lbs= 4.448 N
A spring vibrates with a period of 0.50 s when a mass of 3.0 kg is placed on it. What is the spring constant for this spring?
T=2(pi)*square root of m/k
A 75 lb boy and a 65 lb girl play on a seesaw. The seesaw is 14 ft long and is pivoted exactly in the middle. If the girl sits on the end of her side, where must the boy sit to make the seesaw balance?
F(i)r(i)=F(o)r(o)
The pendulum of a grandfather clock is supposed to have a period of 2.0 s. How long should the pendulum be in meters?
T= 2(pi)*square root of l/g
