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F=ma
Friction
Energy
Kinematics
Potpourri
100
This is the resulting force that actually causes the acceleration of an object.
What is net force?
100
Why does every situation have two mu's?
Static and kinetic friction.
100
If an object is moving without changing its elevation, what kind of energy does it have?
Kinetic energy.
100
How far will a car go if it accelerates at 5 m/s^2 for 10 seconds, and it starts from rest?
250 m
100
Inertia is an object's tendency to resist this.
What is acceleration or net force.
200
Similar to gravity and zero, this animal does not care at all.
What is the honey badger.
200
Describe a situation where the normal force on an object is greater than the weight of the object. Less than?
Answers will vary.
200
If an object is dropped from 2 meters and is now at 1 meter, how fast is it moving?
sqrt(20) m/s
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 rolling 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 by 3 seconds.
200
You are swinging a tethered rock above your head. When the rock is directly in front of you, which way is your arm pulling on the string?
Directly backwards.
300
Find the resulting force: 30N North, 40N East, 20N Southwest.
What is 30.33N 31.5 degrees North of East
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
Three balls start off at the same height on three difference ramps. One ramp is a straight 2 meters long. The second ramp is curved and is 2.4 meters long. The third ramp is straight but is only 1.5 meters long. Which ball will be going the fastest when it leaves its ramp? Neglect friction.
They will be equally as fast.
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.
300
Describe the difference between centrifugal and centripetal force.
Centrifugal is a pseudo force caused by the environment accelerating around an object. Centripetal is the real force that moves an object towards the center of its circular trajectory.
400
Boris and Nadia are having a lover's spat over the placement of their new refrigerator. Nadia is pushing with 200N, and Boris is pushing back in the opposite direction. If the fridge has 75kg of mass, and is accelerating forward at 2m/s^2, what is the value of Boris' push?
Boris is pushing back with 50N.
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
Explain the term "entropy."
The tendency for all natural system to moves towards disorder. We see this in physics commonly as the loss of energy to heat (random vibration)
400
A spaceship fires its reverse thrusters (6,000 N) so that it can land on its mother ship at a safer speed. If it is moving at 30 m/s and has 300 kg of mass, how long until it comes to a stop? Will the pilot feel more or less than one "g"?
What is 1.5 seconds. Yes, the pilot will feel greater than 2 g's.
400
Which is more difficult to control and why? Fusion of fission?
Fusion. Fission is a naturally occuring process on Earth with many radioactive elements. Fusion only occurs naturally in high pressure environments, like the sun.
500
What is the force down the ramp on a 30kg object if the ramp is inclined at 25 degrees?
126.79N
500
A 200 kg snowmobile has stalled in powder on a 20 degree incline. The driver must now push the sled up the hill. The coefficient of kinetic friction is 0.65. How hard will the driver have to push to keep the sled at constant speed up the hill? Will she have to push harder or softer to get the sled moving in the first place?
1906 N. Harder.
500
A man wearing a jetpack (120 kg) has 1 MJ of fuel. He fires his rocket and shoots straight up. How much fuel does he have left when if he is moving at 30m/s and is 500m up?
346,000 J remaining
500
What velocity did yer scurvy cannon ball leave yer briny cannon if it reaches the merchant ship 20 meters away in 4 seconds?
20.6 m/s @ 76 degrees.
500
What would the value of "g" be on a planet that is twice the size of earth (twice the radius and twice the mass). Is this planet denser than Earth?
About 5 m/s/s. Only 0.25 as dense as Earth.