Show:
F=ma
Energy Conservation
Friction
Data Analysis
Kinematics
100
Explain the concept of "Net Force."
When using F=ma, you must add/subtract all of the forces, and whatever is left over is the net force that the object actually feels.
100
If an object has the ability to fall is has what kind of energy?
Potential [PE=mgh]
100
What does mu stand for?
The coefficient of friction. Stickiness. Usually between 0 and 1, the higher the number, the more friction.
100
What is the difference between standard deviation and a chi-reduced test?
Standard deviation is applied to numbers that are trying to measure the same thing (trials). It tells you how trustworthy an average is. The chi test is done to many averages, and tells you if your data matches a hypothesis (usually only do one per experiment)
100
How far will a car go if it accelerates at 5 m/s^2 for 10 seconds, and it starts from rest?
250 meters
200
If a force points at an angle, what must you do in order to add it to another force?
Break it into its x and y components using trig. Then add all of the x components, and all of the y components to make the legs of a new triangle.
200
If an object was dropped from 2 meters high, and is currently at a height of 1 meter. What kind of energy does it have?
Potential and Kinetic.
200
What is the normal force, and how does it play in to the idea of friction?
The normal force is a reactionary force that points perpendicularly out of a surface that keeps the object from passing through the surface. The more normal force and object feels, the more friction resists motion.
200
Why do we use our standard deviations in the chi test?
Standard deviation gives you a picture of how much error you have at that level. Chi asks the question, "does this data point fit this hypothesis within the error of the experiment."
200
A Honda Civic is approaching a red light. A Ferrari is stopped at the red light. As soon as the Civic reaches the intersection the light turns green. If the civic was moving at 10 m/s and then pushes the accelerator to 4 m/s^2, and the Ferrari pushes the accelerator to 10 m/s^2. Who would win a 500 meter race?
The Ferrari gets there 3 seconds ahead.
300
Find the resulting force: Force 1: 30N North Force 2: 45N Northeast Froce 3: 60N Southeast
Net Force = 77N @ 14.7 degrees North of East
300
Two balls start off at the top of ramps that are 3 meters high. The first ball rolls down rolls down a short steep ramp, and the second rolls down a long shallow ramp. Which one ends up with the greatest speed? Which one experienced the greatest acceleration?
Neither. Ball 1 (but for a shorter time)
300
What is the static friction threshold on a 5 kg object sitting on a flat surface. The coefficient of static friction is 0.8. Why do we use the word "threshold?"
40N. Because that's the amount of force it takes to get the object moving, below that friction perfectly opposes any force.
300
Which one of these data sets has the best standard deviation:
Data Set 1 Data Set 2
3 5
1 7
3 6
15 10
What is Data Set 2 (0.9)
300
A spear is thrown at 30 degrees above level at 10 m/s. How long is it airborne, and how far does it go?
1 second, 8.66 meters.
400
Boris and Nadia are having a lover's spat over the placement of their new refrigerator. Nadia is pushing with 100N, and Boris is pushing back in the opposite direction. If the fridge has 120 kg of mass, and is accelerating forward at 1m/s^2, what is the value of Boris' push?
Boris pushes with -20N
400
A roller coaster starts is half-way through its ride, and is at the top of a 10m hill. How much speed does it need to have at the top of this hill to be able to just get to the top of the next 15m hill?
10 m/s
400
An object is being pushed on with a 500N force. The object has 50 kg of mass. The coefficient of static friction is 0.9. The coefficient of kinetic friction is 0.5. Will the object move? If so, with what acceleration?
Yes. 5 m/s^2
400
Two students design an experiment to test the effect of the mass of a ball on the time it takes to fall down the balcony. All of the balls they used have the same radius. Their data shows a slightly downward sloping line. What is the independent variable, dependent variable, controls, and why do they see a slightly downward sloping line?
IV=Mass
DV=Time to fall
Control=radius
Most likely the drag force on the lighter balls was greater, causing the times are lower mass to be slightly higher.
400
What speed will a projectile have in the y-direction 3 seconds after it is released at 45 m/s at 50 degrees? Is this on the first or second part of the arc?
4.5 m/s. Still in the first half, the y velocity would be negative on the second half.
500
What is the acceleration of an object on a 25 degree incline?
4.2 m/s^2
500
The bumper of a car is supported by a spring with k=8000N/m. How far will the bumper of a parked car depress if another car (500kg) crashed into it at 15m/s?
3.75 m (i.e. broken)
500
A matchbox car is loaded into a spring launcher. The spring has k=100N/m and is compressed 10cm. The car has mass 50g, and experiences a coefficient of static friction of 0.3. How far will the car go when the spring is released?
3.33 meters
500
Two students did an experiment about how the height of a drop effects the speed at which an object strikes the ground. Their data follows: 4.54
Height(m>Speed(m/s)
00
1
26.5
37.75
9
What hypothesis should the students try to fit to their data? Draw a graph of their data to see if your hypothesis makes sense.
v = sqrt(2gh)
500
What speed did yer scurvy cannon ball leave yer briny cannon if it reaches the merchant ship 20 meters away in 4 second?
20.6 m/s @ 76 degrees.