Uark college physics I final

Ball A is launched at 20 m/s at an angle of 30° above the horizontal. Ball B is launched at 20 m/s at an angle of 75° above the horizontal. Which one has a larger maximum height?

ball B

Planet Razorback orbits its star in a circular orbit at a constant speed. What direction is its acceleration?

Toward the star

what are examples of vectors?

Displacement, acceleration, velocity. speed is not a vector.

How is 0.00058130 correctly rewritten in scientific notation?

5.81×10^-4

The acceleration experienced by a basketball as it moves through the air toward the basket, on Earth, ignoring air resistance, is:

In the downward direction the entire time it is in the air

When an object experiences acceleration, the velocity is:

changing in magnitude/direction

A lab setup can be adjusted to launch balls horizontally from the same height at 10 m/s or 20 m/s. Which setting results in the ball being in the air the largest amount of time? Assume no air resistance.

the balls hit the floor in the same amount of time

As a box slides up a frictionless incline on Earth, what can be said about its acceleration?

The acceleration is down the slope

A golf ball is hit into the air. Ignore air resistance. As it moves in its trajectory to its highest point (x is horizontal, and y is vertical):

Vy decreases, Vx is constant

You ask your roommate to toss you an orange. As you watch it move through the air, you realize that at its highest point:

The acceleration is down, and the velocity is horizontal

You throw a pillow straight up into the air. What can be said about the motion at the highest point?

Velocity is zero, acceleration is not zero

A ball rolls in a straight line across a table with an unchanging speed. The acceleration must be:

zero

You throw a ball for your dog to chase. What happens to the horizontal component of the velocity, Vx, as it moves through the air? Assume there is no air resistance.

it is constant

In a motion diagram, if the dots get farther apart with increasing time, the object is:

moving with increasing speed

How many significant figures are in 0.00360?

3

A car is traveling at a constant 25 m/s on a level road. What is the linear speed at the top and bottom of a tire?

The top is 50 m/s, the bottom is 0 m/s

Two small balls with the same mass attract each other gravitationally with a force of F. If the distance between the balls is increased by a factor of 4, but the masses remain the same, what is the magnitude of the gravitational force on each one?

F/16

You drop a shoe on the floor. Which one experiences the larger force during the collision?

they experience the same force

The normal force on a stationary child with mass M on a slide at an angle θ above the horizontal is

Mgcos θ

Three forces of equal magnitude are applied to a door separately. Force A is perpendicular to the door halfway between the hinges and the doorknob. Force B is perpendicular to the door at the doorknob. Force C is at a 45° angle to the door at the doorknob. Which force produces the largest torque about the hinges?

Force B

You are sliding a stack of chairs across a stage in preparation. If the force you apply is 12° below the horizontal, how does the normal force of the floor on the stack compare to the weight of the chairs?

The normal force is larger than the weight

Phobos is a small moon orbiting Mars. Which one experiences a larger gravitational force?

They experience the same force

You are pulling a chair up a ramp into a moving van. The chair is moving at a constant speed. What direction is the net (total) force on the chair?

Zero

A child swings a ball on the end of a string in a vertical circle. When the ball is moving upward, and the string is horizontal, the string breaks. What happens to the ball?

it goes straight up in the air

You want to slide your couch to the other side of the room. Which requires a larger force, getting it moving, or keeping it moving? Why?

getting it started because fs > fk

In order for a ball to move at a constant speed along a circular path, its acceleration must:

point directly at the center of the circle

Two small balls with the same mass attract each other gravitationally with a force of F. If the distance between the balls is tripled, but the masses remain the same, what is the magnitude of the gravitational force on each one?

F/9

A disk is spinning about its center at a constant rate. A red dot is at the edge of the disk and a green dot is halfway between the edge and the center. What can be said about the motion of the dots?

The dots have the same angular velocity, but the red dot has a larger tangential velocity.

A rock in deep space, far from other objects, moves in a straight line at a steady 43 m/s. What can be said about the forces acting on the rock?

No forces act on it, or the net force is zero

You throw 2 balls with the same amount of force. The red ball has 3 times the mass of the green ball. How do the accelerations of the two balls compare?

the green ball has 3 times the acceleration of the red ball

A football is kicked into the air. What is the sign of the work done by gravity as the ball goes up and then comes back down?

negative on the way up, positive on the way down.

A small box slides across a smooth (frictionless) floor and collides with a stationary large box. Neither mass is known. The two boxes stick together. What can be said about the momentum of the boxes after the collision?

The momentum of the system is conserved but not each box

Two balls are dropped to the floor from the same height. One has a mass of 100g. The other has a mass of 300g. How does the change of potential energy compare for the two?

The change for the 300g ball is 3 times that of the 100g ball

A ball launcher is used in the lab to launch 3 balls at the same speed from the same height. The blue ball is launched straight up, the red ball horizontally, and the yellow ball is launched straight down. If there is no air resistance, which ball reaches the ground with the largest speed?

All reach the floor with the same speed

As cold milk is stirred into hot coffee, the entropy:

increases

Two concrete posts have the same height but different diameters, 20 cm and 30 cm. A 200 kg box is balanced on each post separately. Which post will compress more?

The 20 cm post

Two objects collide and stick together. Which statement is true?

Final total momentum is equal to initial total momentum

A student sits on a spinning lab stool (frictionless axle) with her arms down by her side. As she spins, she raises her arms out to her sides. What happens to her moment of inertia and angular velocity?

Moment of inertia increases, angular velocity decreases

Which of these indicates a higher temperature: running a fever of 1.5°F, 1.5°C, or 1.5K above normal?

1.5°C and 1.5K are the same difference and larger than 1.5°F, therefore worse

Students C and D do the same amount of work, but C does it in 3 times the time. C's power output is:

1/3 of D's

Doof and Shmirtz are trying unsuccessfully to move a large rock. Doof pushes for 6 minutes with a force of 600 N. Shmirtz pushes for 9 minutes with a force of 900 N. Compare the amount of work they each do on the rock.

Neither does any work

A 987 N force is applied to 2 steel cables, that are the same diameter. One is 8.0 m long and the other is 9.0 m long. Which one stretches the most?

The 9.0 m long cable

A cat sits near the end of a board with two supports beneath it. What must be true to be able to say that the board is in static equilibrium?

Net torque and net force are zero

A red ball and a blue ball have the same mass. The red ball bounces very well, but the blue ball sticks to the floor and doesn't bounce at all. They are dropped from the same height. Which statement below is true about their interactions with the floor?

The red ball has a larger change of momentum than the blue ball

You throw a ball straight up in the air with a velocity V (kinetic energy K) and it reaches a height H. How high will it rise if the initial speed is doubled?

4H