midterm 2 Flashcards
If there was a closed hydraulic system, and one side had a surface area of 100 in2 and the other side had a surface area of 10 in2. What would be the output force on the large end (100 in2) if the small end (10 in2) was pushed with a force of 10 pounds?
100 pounds
If there were two balls completely submerged in water called ball Q and ball P. If the balls had the same mass, and ball Q had a volume larger than ball P, what do you know about the gravitational and buoyant forces?
The gravitational force is the same for both balls and the buoyant force is greater for ball Q than ball P.
Pressure only depends on the surface area of the fluid and does not depend on the depth.
False
Where would you expect the air pressure due to our atmosphere to be largest here on Earth?
sea level
If you had three fluids A, B, and C. One way to determine the relative densities of fluids A, B, and C is to mix them together. Over time the most dense fluid will rise to the top, and the least dense fluid will sink to the bottom.
false
Special Relativity only works when all objects are not accelerating.
true
According to special relativity no information can go faster than the speed of light. That means if the Sun disappeared the people on Earth would not know it was gone for about 8 min and 20 sec.
true
If someone was traveling close to the speed of light in a spaceship and the had a stick that was one meter long pointed in the same direction as the spaceship was traveling. What would an outside observer say about the meter stick?
The stick is shorter than one meter
If someone was traveling close to the speed of light in a spaceship and the had a clock that was started and stopped after 10 seconds. While the clock was ticking an outside observer started and stopped at the same time. What would an outside observer say about the measured time?
The outside observer would say the time was greater than 10 sec.
What is pressure? How can you determine if something has higher or lower pressure?
total force on an object divided by area over which the force is applied. Pressure = force/area.
increase force-increase pressure. decrease area-increase pressure.
How can you calculate the output force for a closed hydraulic system if I tell you the input force, and surface area of both sides?
PressureLeft = PressureRight ForceL/AreaL = ForceR/AreaR
What do we know about the pressure due to the atmosphere here on Earth?
They are unbounded fluids. Pulled to center of earth by gravity. It gets stronger in depth.
What if you had two balls with the same masses but different volumes? What would be their gravitational and buoyant force?
gravity pulls down and buoyant force pushes upward. object accelerates in direction of net force (direction of stronger forces).
bigger volume has more buoyant force against it while the smaller has less. equal gravity.
What if you had two balls with different masses but the same volume? What would be their gravitational and buoyant force?
bigger mass/weight has more gravity force against it while the other has less. equal buoyant force.
What is the definition of density?
density= mass/volume
What is the fastest information can travel in the universe?
at the speed of light. 670,000,000mph
How does an outside observer measure your time and length when you are going really fast (close to the speed of light?
time is longer, length is shorter
If you are not accelerating is there anyway to tell if you are moving?
by using Inertial Frame of Reference. the laws of nature remain the same for all observers in inertial frames of reference. like we stand still but to the earth we move. RELATIVITY.
What did the Michelson Morley teach us about light? (I went over this in class for little while. Look in your book or look online for more information)
Light travels at the same speed no matter what direction.
- Speed of Light same for everyone.
- The laws of physics are same for everyone (no acceleration). doesn’t follow galilean relativity.
How does kinetic energy work?
energy of motion.
KE= 1/2mass * speed^2
What is gravitational potential energy?
stored energy in an object that has potential to fall.
GPE = weight * height
What is potential energy? How can you increase the potential energy between charges?
stored energy.
moving positives together.
moving opposites away from each other.
What is work in physics?
how energy is spent.
work= force * displacement
How is kinetic energy and potential energy related for the pendulum?
They are constantly moving for kinetic but their is potential for it to fall cause of gravity.
What are convection, conduction, and radiation? Can you think of an example of each of these heat transferring processes?
convection: hot materials moves and transfers its heat to colder material.
- firemen running the buckets back and forth to fire.
conduction: objects having different temperatures are placed in direct contact with each other. no perceptible motion.
- firemen passing buckets from one to another.
radiation: direct transfer of energy from one place to another without any need for intervening matter.
- firemen spraying fire from source.
There will be a conservation of momentum problem. I will give you the masses of two cars. One car will hit another car at rest. After the collision the first car stop. Given that you know the starting speed of one car can you calculate the new speed of the car that was hit?
MV(before)=MV(after)
solve for V
This is the exact question: If there was a small car with a mass of 1,000kg traveling at a velocity of 20m/s (45mph) that collided with a semi truck at rest 10,000kg. Assuming the small car stopped at impact what is the truck’s speed after impact? (Hint conservation of linear momentum)
2 m/s
Conservation of Mass:
Conservation of Mass: mass always the same after physical process.
Ex. Baking cookies. dough same as ingredients. add steam with baked and the same again.
Conservation of Charge:
Conservation of Charge: moving charge of electrons.
Ex. rubbing ballon on head. doesn’t create new charge, just redistributes
Conservation of Energy:
that energy can be neither created nor destroyed. 1st law of thermodynamics.
ex. dropping a rubber ball and it bouncing back.
Conservation of angular momentum:
AM= massvelocity(speed)radius.
ex. top, spinning faster it can balance
conservation of linear momentum
LM=Mass*Velocity, measures amount of motion in a straight line.
ex. car wreck, what ways they went and tire skids. Pool, what way the ball will go.
