Motion
What is motion?
The process of changing position
What is energy?
The ability to do work or cause change
What is a wave?
A traveling disturbance that transfers energy from one place to another but does not transfer matter
What is the velocity of a person that hopped 5 m to the right in 2.5 s?
2 m/s to the right
What are the steps of the scientific inquiry process?
Ask Questions
Hypothesize and Predict
Test Hypothesis
Analyze Results
Draw Conclusions
Communicate Results
You release a toy car down a ramp. The car eventually stops after rolling down the ramp. Which of Newton's Laws explains why the car stops?
Newton's First Law
(An object in motion stays in motion unless acted upon by an outside force. Sliding friction is the force acting against the motion of the car causing it to stop)
At what point on a roller coaster ride is there the greatest amount of potential energy?
At the highest point
What is diffraction?
the change in direction of a wave when it travels by the edge of an object or through an opening
Rafiki holds Simba 35 meters in the air at the top of Pride rock. If Simba has a mass of 1.4 kilograms, what is his potential energy when held up by Rafiki? (assuming they are both on Earth and g=9.8m/s2)
PE = m x g x h
PE = 1.4kg x 9.8m/s2 x 35m
PE = 480.2 J
How can you tell on a distance time graph that an object stopped moving?
The slope of the line is 0 (a horizontal line).
The distance stays the same as the time increases.
What are the 3 ways in which velocity can change?
1. Change in speed
2. Change in direction
3. Change in speed and direction
What is the difference between conduction, convection and radiation?
Radiation is the transfer of thermal energy from one material to another by electromagnetic waves
Conduction: the transfer of thermal energy between materials by the collisions of particles (in contact)
Convection: the transfer of thermal energy by the movement of particles from one part of a material to another (in fluids)
What are the 7 types of waves on the Electromagnetic Spectrum?
Radio waves, Microwaves, Infrared Waves, Visible Light (Light Waves), Ultraviolet Waves, X-Rays, Gamma Rays
A car is driving North on a highway. At 6 seconds it is traveling at 20 m/s. It then speeds up and at 10 seconds it is still traveling North but now at a speed of 32 m/s. What is the acceleration of the car?
a = (vf-vi) / t
a = (32 m/s - 20 m/s) / (10 s - 6 s)
a = 12 m/s / 4 s
a = 3m/s2
What number is represented by the following binary code: 100100
36
(32x1)+(16x0)+(8x0)+(4x1)+(2*0)+(1*0)=36
An in-line skater uses two hands to push against a wall in front of her. Explain why she rolls backward (there are 3 forces involved that you must explain).
The skater exerts an action force on the wall; the wall exerts a reaction force of equal size but in the opposite direction on the skater.
The reaction force is greater than the force of static friction on the skater, so the skater rolls backward, away from the wall.
Explain one benefit and one limitation of solar power.
Benefits: it is better for the environment (does not produce air pollutants or carbon dioxide which results in cleaner air and water); it is an inexhaustible energy resource (cannot be used up)
Limitations: the amount of sunlight available is not constant (varies depending on location, time, season, and weather), a large surface area is need (can negatively impact habitats for plants and animals)
Why do you get a sunburn if you are out in the sun for too long without sunscreen, but your skin doesn't burn when you shine a flashlight on it?
Ultraviolet waves have a higher frequency than light waves. Higher frequency means more energy carried by the waves. So ultraviolet waves from the Sun carry enough energy to damage skin cells. Light waves (lower energy) from a flashlight do not.
An object with a mass of 2300g has a force of 10N applied to it to push it to the right. There is sliding friction acting against the motion to the left at a force of 0.8N. What is the acceleration of the object?
f = m x a
a = f / m
net force (f) = 10N - 0.8N = 9.2N
mass (m) = 2300g/1000 = 2.3kg
a = 9.2N / 2.3kg
a = 4 m/s^2
Draw an example of a speed-time graph that represents an object slowing down and coming to a stop (including correctly label x- and y-axis)
A line with an downward slope, end touching the x-axis
X-axis = time
Y-axis = speed
What are the 3 types of friction? Provide an example for each
Static Friction: If you push on a boulder alone, static friction would be the force opposing you if you are unable to move the boulder (it stays stationary even when you push on it)
Sliding Friction: If you and a friend push on a boulder together and it moves forwards, sliding friction would be the force opposing you trying to stop it from moving
Fluid Friction: If you drop a piece of paper, gravity is the force pulling the paper down towards the ground and fluid friction in the form of air resistance is pushing up on the paper trying to stop the paper from falling
Explain why the pot itself is made of metal, while its handle is usually made of a plastic.
The metal pot allows thermal energy to flow through it easily so it is a thermal conductor. This allows the burner on the stove to heat up whatever is inside of the pot to cook it.
The handle of the pot is a thermal insulator. The material does not allow energy to flow through it easily. This allows you to touch the pot by the handle without burning yourself even when the contents in the pot are hot (it takes longer to become hot than the pot itself).
If you are holding a flashlight at a 45 degree angle above a mirror that is laying flat on the table, will the light hit an object that is on the wall at a 50 degree angle above the mirror? Why or why not?
No it will not because when a wave is reflected from a surface, the angle of reflection is equal to the angle of incidence, so the light will hit just below the object at a spot 45 degrees above the mirror
Mike Wazowski throws a folder full of paperwork with a mass of 4 kg onto Roz’s desk. If the folder of paperwork is moving at 2 m/s, what is the kinetic energy of the paperwork?
KE = 1/2 x m x v2
KE = 1/2 x 4 kg x (2 m/s)2
KE = 1/2 x 4 kg x 4 m2/s2
KE = 8 J
A popcorn maker is plugged into the wall and then popcorn is made. You and your friends eat it for a snack. (hint, use 5 types of energy in your explanation)
Electrical energy from the popcorn maker being plugged in is converted into thermal energy when the energy is transferred to the heating element of the popcorn maker. The thermal energy is transformed into mechanical energy and sound energy when the popcorn pops. When you eat the popcorn, you convert the energy into chemical energy that your body can use to do activities.