PHY303K Final
What are typical values for the diameter in meters of a nucleus, an atom, and a red blood cell?
(10−15, 10−10, 10−5)
A block of mass m is pulled across across a frictionless table with a constant force. An- other block of larger mass M is also pulled across the frictionless table with the same constant force. If the two blocks start at rest and are pulled through the same distance, which, if either, block has the greater kinetic energy and which, if either, block has the greater momentum. (List the answer to the first question first and separate the answers by a comma.)
Both have the same kinetic energy, M
When you are moving up at constant speed in an elevator, there are two forces acting on you: the floor pushing up on you (F1) and gravity pulling down (F2). What is the relationship between the mag- nitude of F1 and F2 and the physical principle that explains this relationship?
F1 = F2 from the momentum principle.
Does the kinetic energy of the object increase or decrease or stay the same in each of the following four situations?(B) A ball is thrown upward away from the earth with a velocity that is less than the terminal velocity. Air friction acts opposite to the motion.
decreases
Does the kinetic energy of the object increase or decrease or stay the same in each of the following four situations?(D) An elevator moving downward comes to a stop.
decreases
A ball moves in the direction of the arrow labeled d in the following diagram. The ball is struck by a stick that briefly exerts a force on the ball in the direction of the arrow labeled f. Which arrow describes the direction of ∆⃗p, the change in the ball's momentum?
f
Does the kinetic energy of the object increase or decrease or stay the same in each of the following four situations?(A) A ball is thrown downward toward the earth with a velocity that is less than the terminal velocity. Air friction acts opposite to the motion.
increases
Alcohol is a liquid less dense than water, and mercury is a liquid denser than water. Given this information, any object that will float on water
will float on mercury and may float on alcohol.
A chain of mass M composed of metal links is coiled up in a tight ball on a frictionless table. You pull on a link at one end of the chain with a constant force of magnitude F. Eventually the chain straightens out to its full length L, and you keep pulling until you have pulled your end of the chain a total distance d. Assume the chain doesn't lose any energy to the surroundings due to heat transfer. Determine the change in the internal energy of the chain.
(1/2)F L
Despite a very strong wind, a tennis player manages to hit a tennis ball with her rac- quet so that the ball passes over the net and lands in her opponent's court. Consider the following forces: 1. A downward force of gravity. 2. A force by the "hit". 3. A force exerted by the air. 4. A force exerted by the ground. Which of the above force(s) is (are) acting on the tennis ball after it has left contact with the racquet and before it touches the ground?
1 and 3
For small angular displacements measured from the vertical, the equation that governs a pendulum's motion is l d2θ = −gθ. dt2 The angular acceleration can be solved as an explicit function of time. If the angular acceleration α = d2θ/dt2 is given by α = A sin(ωt + φ) what are the units of A?
1/time2
What is the approximate diameter of a copper atom in meters?
10^-10
The ratio of the magnitude of the electric force on one electron from another electron to the magnitude of the gravitational force on one electron from another electron is about how big?
10^42
What is the approximate angular speed, i.e., the order of magnitude, measured in radians per second, of the hour hand of the clock in the UT tower?
10^−4 s−1
Atoms are a few tenths of a nanometer in diameter. About how long does it take light to travel the width of an atom?
10−18 s
If a trapeze artist rotates once each second while sailing through the air, and contracts to reduce her rotational inertia to one third of what it was, how many rotations per second will result?
3
The intensity of sunlight peaks at 500nm. What is the frequency of this radiation?
6 × 10^14 1/s
An object is moving in the xˆ direction. Which of the following statements about the net force acting on the object could be true? A. The net force is in the xˆ direction. B. The net force is in the −xˆ direction. C. The net force is zero
A B C
At the lowest point of its oscillation, consider the case when the forces on a pendulum bob satisfy the following condition: mv2 L =mg where v is the speed of the bob at this posi- tion, L is the length of the pendulum string, and m is the bob mass. Which of the following statements are true? Ia. At the bob's lowest point, the upward string tension and downward gravitational force acting on it exactly cancel each other. Therefore, the rate of change of momentum at this position is zero. Ib. At the pendulum's maximum angle, the speed of the bob is zero and the magnitude of its tangential acceleration is maximal. Ic. The string tension at the bob's lowest point is equal to 2mg.
Ib, Ic
The sketch shows the top view of a merry- go-round which is rotating clockwise. A child jumps on the merry-go-round in three differ- ent ways: I) from the left, II) from the top, and III) from the right. For all three cases, the child lands the same distance from the center.
LI > LII > LIII
A ball attached to the end of a string moves in a vertical circle. Consider four positions in the ball's motion: a) when the ball is at its lowest point, b) when the ball is halfway up and mov- ing up, c) when the ball is at its highest point, and d) when the ball is halfway up and mov- ing down. Denote the power done on the ball by gravity at each point as Pga,Pgb,Pgc,Pgd respectively. Which of the following displays the correct relationship between the power done on the ball by gravity:
Pgd > Pgc = Pga > Pgb
You pull a block of mass m across across a frictionless table with a constant force. You also pull with an equal constant force a block of larger mass M. The blocks are initially at rest. If you pull the blocks through the same distance, which block has the greater ki- netic energy, and which block has the greater momentum, respectively?
Same kinetic energy, M
A truck pulls a trailer with a horizontal force. The reaction to the force that the truck exerts on the trailer is
The horizontal force exerted by the trailer on the truck.
The diagram shows a compressed spring between two carts initially at rest on a hori- zontal frictionless surface. Cart A has a mass of2kgandcartBhasamassof1kg. Astring holds the carts together. What occurs when the string is cut and the carts move apart? Note: Assume forces due to surroundings on the two-cart system are negligible.
The magnitude of the acceleration of cart A is one-half the magnitude of the accelera- tion of cart B
A compact car and a large truck collide head on and stick together. Which undergoes the larger change in the magnitude of momentum?
The momentum change is the same for both vehicles.
The density of ice is smaller then the den- sity of water but larger than the density of oil. Consider a completely submerged ice cube floating in a glass at the interface of water and oil.
The oil level falls and the water level rises.
Suppose there are two objects, A and B, which are known to be interacting with one another. If object B moves in a straight line at a con- stant speed, which statement below must be true?
There is some object other than A also interacting with object B
A projectile fired into the air suddenly ex- plodes into several fragments.
What can be said about the motion of the center of mass of the system made up of all the fragments after the explosion?
What explains why so many physical systems in nature are well-described as a simple harmonic oscillator?
When a system at rest is at a potential energy minimum, the potential energy will in- crease quadratically for small displacements, just as for a spring
Two wires with equal lengths are made of pure copper. The diameter of wire A is twice the diameter of wire B. You make careful measurements and compute Young's modulus for both wires. What do you find?
YA = YB
The more massive Earth and the less mas- sive moon are attracted to each other by the gravitational force. Is the acceleration experienced by the Earth due to this gravitational interaction with the moon is greater than, less than, or the same as the acceleration experienced by the moon?
less than
If instead you pull the blocks for the same amount of time, which block has the greater kinetic energy, and which block has the greater momentum, respectively?
m, same momentum
Does the kinetic energy of the object increase or decrease or stay the same in each of the following four situations?(C) A block slides on a circular horizontal frictionless track.
stays the same
For small angular displacements measured from the vertical, the equation that governs a pendulum's motion is l d2θ = −gθ. dt2 The angular displacement from the vertical can be solved as an explicit function of time. If the angular displacement θ of the pendulum is given by θ = A sin(ω0t + φ) what are the units of A? (ω0 is the constant angular frequency of the motion.)
unitless
