Significant Figures & Converting Units
How many sig figs in 20.0
3
What is the difference between kinetic and static friction?
Kinetic is friction between two moving objects sliding past each other. Static friction is friction between two objects that are touching each other but not moving.
A handicap ramp is an example of what type of simple machine?
Inclined Plane
When jumping on a trampoline, you are demonstrating which of the Newton's Laws?
Newton's Third Law of Motion
Kinetic energy is energy of ____________.
Movement
How many sig figs in 0.02300
4
Name one type of non-contact force
Any of the following answers are fine:
Magnetic Forces
Gravitational Forces
Electrostatic Force
Nuclear Forces
Name all 6 simple machines.
Lever
Inclined Plane
Wedge
Screw
Pulley
Wheel and Axle
What is momentum?
Momentum is defined as hard hard it is to get an object to stop.
Potential energy is considered _________ energy.
stored
20 cm = _____ km
10-2 --> 103
Small to large, move decimal left.
-2, -1, 0, 1, 2, 3 (move 5 spaces)
0.0002
If an machine pushes a 20 kg object 15 m down the hall with a force of 10 Newtons, how much work is the machine doing?
Work = Force x Distance
Work = 10 N x 15 m
W = 150 Joules
What is the purpose of a wedge? Provide an example.
A wedge is used to push two objects apart.
Examples: knife, axe, door stopper, zipper, etc
The idea of inertia is most closely related to which law of motion?
Newton's First Law of Motion
Thermal Energy is considered:
Elastic Energy is considered:
Chemical Energy is considered:
Thermal: Kinetic Energy
Elastic: Potential Energy
Chemical: Potential Energy
Convert 10km to m
10km = 10,000 m
What is the difference between distance and displacement?
Distance is how far something travels along a path.
Displacement is the difference between the starting point and ending point.
Screws are composed of objects. Name them.
Screws are composed of an inclined plane wrapped around a cylinder/tube.
Correct the following false statement:
If an object's mass increases, its acceleration also increases if the net force acting on the object stays the same.
If an object's mass increases, its acceleration decreases if the net force acting on the object stays the same.
A toy with a mass of 10 grams is suspended 20 meters into the air. It takes 2 seconds to hit the ground when it is suddenly dropped. When it hits the ground, how much potential energy does it have before it is dropped?
PE = mgh
PE = (10)(9.8m/s2)(20)
PE = 1,960 Joules
What is the correct answer to the following question, rounding to the correct number of significant figures?
12.25 + 7.4 = 19.7
Even though 7.4 only has 2 sig figs, we need one decimal place because the problem has one decimal place.
An object travels 100 meters in 5 seconds. What is the object's velocity?
Velocity (v) = distance/time
Velocity (v) = 100 meters/5 seconds
v = 20 meters/second
When trying to maximize the efficiency of a lever, you want the fulcrum _________ from the load.
As the length of the lever increases, does the mechanical advantage increase or decrease?
When trying to maximize the efficiency of a lever, you want the fulcrum close to the load.
The longer the lever, the greater the mechanical advantage. Therefore, longer levers increase mechanical advantage.
The force applied to an 10 kg object changes from 5 Newtons to 10 Newtons. What is the change of acceleration?
Force (F) = mass (m) x acceleration (a)
We can rearrange the formula to solve for (a). The difference in force is 5 Newtons.
a = F/m
a = 5N / 5kg
a = 1 m/s2
A toy with a mass of 10 grams is suspended 20 meters into the air. It takes 2 seconds to hit the ground when it is suddenly dropped. When it hits the ground, how much kinetic energy does it have?
K.E. = 1/2 mv2
K.E. = 1/2 (10)(20/2)2
K.E. = 500 Joules