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Science exam
Motion
Identify all the units used to measure motion. Not all possible answers are included, check with your teacher if you are unsure
Example: distance meters, km, ft time min, hr, sec velocity m/s. km/hr acceleration m/s/s or m/s2
Understand how frame of reference is used to determine motion
Example: What is your frame of reference while riding the bumper cars at Bay Beach?
Frame of reference is used to determine motion by comparison, usually a stationary object in the background is compared to the object moving. You know the bumper cars are moving because the people in line are not moving or the tree or the ceiling. You also know you are moving as you get further away from the person who started the ride.
Understand velocity:
Explain what 55 mi/hr means. 55 mi is the distance covered in 1 hour of movement. The change in position from pt A to pt B is 55 miles and it it took 1 hour to do so
Example – Give your own example of when knowing the velocity of an object is important.
Knowing how the velocity of a car compares to the velocity of the cop car. Knowing how
the velocity to determine arrival time on GPS
Example- Explain what the speed of a car going 55 mi/hr is RELATIVE to a police car speeding
past the car @ 95 mi/hr.
The police car looks to be going 40 mi/hr relative to the car or people in the car moving at 55 mi/hr
False: Velocity is calculated by taking the distance x the time it took to travel that far.
Interpret graphs dealing with velocity & acceleration: A = final V - initial V / change in time
Ex – What is the acceleration of an object that begins at rest and after 20 sec is traveling at 100 m/s?
100 m/s - 0 m/s / 20 sec = 5 m/s/s
Example – Draw a distance(position) time graph representing constant velocity of a biker.
The biker was going the same (constant)velocity from A-B and at a constant rate from C-D
Example – Draw a distance time graph representing constant acceleration of a biker.
The curved portions on a DISTANCE TIME SHOW A CHANGE IN VELOCITY OR ACCELERATION
Example- What are the 4 requirements for a “good” graph?
Title, X Y axis labeled, proper units of measurement, and data points(line graph)
Rockets: Identify 3 areas where your rockets will accelerate (Change in velocity) you can draw and label or list your response
When it leaves the launch pad
When it slows down near the max height
As it changes direction and begins to fall
As soon as the parachute deploys
Forces
Explain what a force is and how it changes the motion of objects
Example: Identify a force and explain how the force changes the acceleration of an object.
A force is any push or pull that changes the motion(or velocity) of an object. Gravity is the force that changes the acceleration of a falling object. + acceleration due to gravity or friction is the force that changes the acceleration of a car - acceleration
Understand the difference between balanced and unbalanced forces
Example: Draw a diagram using force arrows to illustrate unbalanced forces
24 N -------------> < --------- 10 N
Identify correct units for measurement of a force
Example: What is a Newton?
Newton is the unit of measurement for force. 1 N = 1 kg x m/s/s
Use the force equation and solve for mass and acceleration. Force = mass x acceleration
Example: What is the force required to move 33 kg at 4.5 m/s/s?
Force = 33 kg x 4.5 m/s/s = 148.5 Newtons
Example: Write your own problem solving for mass and SOLVE IT
A force of 39 Newtons was applied to the box and it accelerated at a rate of 1.2 m/s/s. What was the mass of the box? Mass = force/acceleration 39/1.2 32.5 kilograms
Use a diagram to show balanced, unbalanced, and net forces and acceleration.
Example: Use the diagram below to find the net force and acceleration of the 5 kg box.
ANSWER: 10 N to the right; Acceleration = 2 m/s/s
Understand the concept of friction and how it affects motion
Example: Draw a couch being pushed horizontally and identify the frictional force.
Use force arrows in your drawing Net force is 12 N right
20 N --------------> < ---8 N (frictional force to the left working against)
Example – Identify where the fluid friction is affecting a meteor as it is passing through earth’s atmosphere?
The meteor is being slowed down by the atmosphere- so much friction it bursts into flame???
Example: How does friction affect the path of your ROCKET on the way up?
Drawing your response is acceptable
Air resistance(friction) begins to slow down the rocket the second it leaves the launch pad
Be able to state Newton's 1st and 2nd Laws of Motion
Example: Use your knowledge of INERTIA to explain objects at rest and objects in motion
An object with a lot of mass will have a lot of inertia so it will want to remain at rest
A moving object with a lot of mass will want to remain moving
Force = mass x acceleration
Law 1: Ex – Which rock has more inertia, a 1 kg rock traveling 5,000 m/s or a 1,000 kg rock traveling
2 m/s? The 1 kg rock has more inertia moving at 5,000 m/s
Law 1: When do ROCKETS demonstrate Newton’s 1st Law? AT rest on the launch pad and as it is moving it wants to stay moving however gravity and friction(air resistance) are the outside forces affecting the rocket’s motion
Law 2: Example: Use 2 Amazon boxes to explain your understanding of Newton’s 2nd Law
More force is needed to accelerate the box with more mass. More force is needed to stop the box with more mass if it were moving/accelerating.
Understand the concept of gravity and what factors affect acceleration due to gravity
Example – Why is gravitational force less on the moon 1.6 m/s/s vs Earth 9.8 m/s/s?
Gravity is based on the mass of the objects and the moon is less massive than earth.
Ex: Why will a soccer ball and a ping pong ball hit the ground at the same time in a vacuum?
Without air resistance, objects will fall at the same rate since the force of gravity acts on each object differently to create the same acceleration.
Ex: Draw a rock falling from a cliff for 5 seconds and illustrate how the velocity of the rock
changes until it hits the road.
Your answer may be slightly different if you added air resistance… but if there is no air resistance, then the box only has gravity acting in the downward direction and thus it will keep accelerating until it hits the ground and stops abruptly.
Ex- How does the velocity of your rocket change on the way back down to earth?
Think about potential and kinetic energy Explain why
Velocity increases as the potential energy is converted into kinetic energy by the work applied to the rock over time by gravity.
Be able to relate mass, force, and friction to an situation
Example- What is the force exerted on your desk when a 10 kg box is sitting on your desk?
f=m*a f=10kg*9.8m/s/s f=98N
Example- What is the mass of the box?
10kg
How much force does the desk push back on the box with?
98N because it is not accelerating.
What is the net force acting on the box?
Zero because it is not accelerating.
Are the forces balanced or unbalanced?
balanced
Where is friction acting on the box resting on your desk?
Where the 2 surfaces are in contact with each other, on the desktop
Waves: Waves, Sound & Light
Understand the relationship between frequency, wavelength and energy of the electromagnetic spectrum
Example – What types of waves on the electromagnetic spectrum have more energy than visible light?
In increasing order of energy- UV, x-ray, gamma ray.
Example: What are the units of measurement for the frequency and wavelength of a wave?
Frequency-hertz hz wavelength-meters
Describe the properties of a wave
Example – Which type of waves require a medium?
Mechanical/ longitudinal waves.
Example – How does density of the medium affect the wave’s behavior?
Mechanical/longitudinal waves speed up as the medium gets more dense
Transverse waves slow down as the medium gets more dense
Know the difference between a transverse and longitudinal wave.
Example – Draw a longitudinal wave and label the compression and rarefaction of the wave.
Example – Draw a transverse wave and label the crest, trough, wavelength, amplitude, and resting position.
Example- What is the speed of light and the speed of sound? Use an example of this in your life.
Speed of light is crazy fast- 3*108m/s. Speed of sound is 346m/s.
This is why you see lightning way before you hear thunder.
Understand wave interaction
Example- Draw a wave encountering constructive interference
Example- Draw a wave illustrating destructive interference
Reflect back to your wave project and connect waves to your life.
Example- What was the topic you researched/presented?
On your own
Example - How did your topic relate to wave interaction?
On your own
Energy
Compare Kinetic and Potential Energy
Example : Explain why a rock has more kinetic energy than a feather when it falls in a vacuum?
If they both start at the same height, a rock will have more mass and thus more potential energy. So even though they will be going the same velocity, the more massive object will have more energy.
Example: Where is your rocket experiencing maximum KE? And Minimum PE?
Max KE is tough with the engine doing a constant push, friction, gravity, and the parachute. But probably right after the engine “shuts off.”
Max PE is at the tallest point.
Where are both KE and PE present?
After take off and right after it changes direction (O KE) at the tallest point and begins the descent towards earth
Be able to calculate GPE using the equation GPE = mass x height x gravity
Example – A 2 kg rock has a GPE of 3,400 J when it is held over the edge of a cliff. How tall is the cliff?
m=2kg pe=3,400J h=pe/(m*g) h=3,400J/(2kg*9.8m/s/s) h=173.5 m
Be able to calculate KE equations. KE = .5 mass x velocity2
Example – What is the velocity of a 4,500 kg rocket with a KE of 100,000 J?
m=4,500kg ke=100,000J v2=100,000j/(0.5*4,500kg) v2=44.4 v=6.67m/s
Example- What is the velocity of a biker if her mass is 45 kg and she has 900 J of KE?
m=45kg ke=900J v2=900J/(0.5*45kg) v2=40 v=6.3m/s
Example- What is the mass of a ball with 200 J of KE traveling at 5 m/s
KE = 200 mass= ? v = 5 200 = .5 m x 25 mass = 16 kg
Know how the Law of Conservation of Energy applies to a roller coaster or pendulum
Example: How is energy conserved as a roller coaster descends from the tallest peak?
Maximum height means max potential energy. Then as it falls, the potential energy is transferred into kinetic energy. That is how roller coasters get going so fast at the bottom of the hills.
Example: How is the law of conservation of energy upheld using Newton’s cradle, if there were no friction
If you lift one ball up in Newton's cradle, you have given it potential energy. Let it go and all of the potential becomes kinetic just before it hits the other balls. This kinetic energy gets transferred to the one on the far side, which goes up to the max height as it all becomes potential energy again. Then the process repeats itself forever if there is no friction.
Example: Think about launching your rocket, Identify where the Law of Conservation is applied when your rocket takes off from the launch pad and reaches its maximum height.
Energy cannot be created or destroyed. So the kinetic energy of the rocket moving has to come from the kinetic energy of the engine. Then all of that kinetic energy becomes potential at its max height.
Know the work equation and apply it to a “working” scenario
Example: What is a joule? A Newton- meter which is
A measure of energy.
Example: Explain how adding extra cotton balls decreased the force experienced by the egg.
Adding extra distance to the impact lessens the force at any given instant. Just like the crumple zone of a car.
List 6 different forms of energy
Example: During rocket launch, what forms of energy are used?
Electricity is used to ignite the engine which uses chemical energy to create kinetic energy which becomes potential energy and then eventually falls back down as kinetic energy. Along with some sound and light energy being lost along the way.
Example: Use a skateboarder to explain mechanical energy
Mechanical energy is the total of kinetic and potential energy. A skateboarder can use this on a ramp by starting with high potential at the top, and then converting it to kinetic as they roll down the ramp.
Understand how nuclear energy converts to electrical energy.
Example: What occurs during the fissioning of U-235? How do the Nuclear Power Plant convert the PE of the uranium pellets into electricity?
U-235 splits into smaller particles (Ba and Kr) and releases energy and then heat turns water into steam which turns a turbine generating electricity
Example: Where does fusion occur?
Most commonly at the center of the sun, but humans are starting to use it a little.
What are 2 reasons we should or should not use nuclear energy?
Should- cost, air quality, ease, safety, more efficient and safer than coal
Should not- cost, location of the spent fuel, mining, non-renewable
Electricity
Know how electrical circuits work.
Example -What are the parts of a circuit?
Power source, wire, resistor (light bulb, fridge, phone battery)
Example -What are different ways a circuit will “open”?
Use a switch to open it on purpose, the resistor breaks, fuse melts, GFCI switch pops or a short circuit occurs
Example- Use Ohm's law to explain how resistance affects the current and voltage of a circuit.
V=I*R so if voltage (potential difference) remains constant, then I and V will be inverse (opposite).
Example: What is the resistance of a circuit if there are 5 amps moving through a 120 volt circuit?
I=5a V=120v R=V/I R=120v/5a R=24 Ohms
Know how series and parallel circuits are different
Example: Draw a series circuit and label how current changes throughout
Adding more resistors in series increases the total resistance of a circuit
As resistance increases, current decreases_____________
Example: Draw a parallel circuit and show how current changes when a light bulb is removed.
Adding more resistors in parallel decreases the overall resistance of a circuit. (more paths for e to flow)
As more paths are added to parallel circuit, current ____increases__________because there is __________less resistance____________________________________________________.
Example- What is the advantage of using a parallel circuit in our homes?
If one outlet or light goes out, the other things stay on.
Science Inquiry
After studying about recycling, members of John’s biology class investigated the effects of various recycled products on plant growth. John’s lab group compared the effect of different aged grass compost on bean plants. Because decomposition is necessary for the release of nutrients, the group hypothesized that older grass compost would produce taller bean plants. Three flats of beans plants (25 per flat) were grown for 5 days. The plants were then fertilized as follows: flat A – 450 g. of 3 month old compost, flat B – 450 g. of 6 month old compost, flat C – 0 g. of compost. The plants received the same amount of sunlight and water each day. At the end of 30 days, the group recorded the height of the plants in cm.
Identify the following parts of an experiment
1.Hypothesis (prediction): older grass compost will produce taller bean plants
2. Dependent Variable: plant ending height
3. Independent Variable: age of compost fertilizer
4. Constants: same amount of sunlight and water, same time, same measuring method
5. Control Group:flat C- no compost
6. Possible sources of error: human error with measuring and watering, sunlight if outside, more trials needed
7. Claim: 6 month old compost helps with growth the most
8. Evidence used to support your claim: Flat B had the best growth height.
Qualitative:observational data based on descriptions and feelings
Quantitative:numerical data usually gathered using a device such as a ruler or meter.
Do you know your units? Let’s find out.
Fill in the missing boxes with the common unit of measurement used