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Beginner
Conceptual
GQ

A solid sphere is rotating about an axis through its center at a constant rotation rate. Another hollow sphere of the same mass and radius is rotating about its axis through the center at the same rotation rate. Which sphere has a greater rotational kinetic energy?

Advanced
Mathematical
GQ

A spacecraft somewhere in between the Earth and the Moon experiences zero net force acting on it. This is because the Earth and the Moon pull the spacecraft in equal but opposite directions. Find the distance \(D\) away from Earth such that the spacecraft experiences zero net force. The distance between the Moon and Earth is \(\sim 3.844 \times 10^8 \, \text{m}\).

Note: You may need the mass of the Earth and the Moon. You can find this in the formula table.

Beginner
Mathematical
GQ

A trash compactor pushes down with a force of \( 500 \) \( \text{N} \) on a \( 3 \) \( \text{cm}^2 \) input piston, causing a force of \( 30,000 \) \( \text{N} \) to crush the trash. What is the area of the output piston that crushes the trash?

Intermediate
Mathematical
GQ

A person whose weight is \(4.92 \times 10^2 \, \text{N}\) is being pulled up vertically by a rope from the bottom of a cave that is \(35.2 \, \text{m}\) deep. The maximum tension that the rope can withstand without breaking is \(592 \, \text{N}\). What is the shortest time, starting from rest, in which the person can be brought out of the cave?

Beginner
Conceptual
GQ

Two closed containers look the same, but one is packed with lead and the other with a few feathers. How could you determine which has more mass if you and the containers were orbiting in a weightless condition in outer space?

Beginner
Conceptual
MCQ

An ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body. What happens to his angular momentum about the axis of rotation?

Advanced
Mathematical
MCQ

An object undergoes constant acceleration. Starting from rest, the object travels \( 5 \, \text{m} \) in the first second. Then it travels \( 15 \, \text{m} \) in the next second. What total distance will be covered after the 3rd second?

Beginner
Proportional Analysis
GQ

You try to open a door, but you are unable to push at a right angle to the door. So, you push the door at an angle of \( 35^{\circ} \) from the horizontal. How much harder would you have to push to open the door just as fast as if you were to push it at \( 90^{\circ} \)?

Beginner
Conceptual
MCQ

Five forces act on a rod that is free to pivot at point \( P \), as shown in the figure. Which of these forces is producing a counter-clockwise torque about point \( P \)?

Intermediate
Mathematical
MCQ

Two points, \( A \) and \( B \), are in a pipe carrying a flowing ideal fluid. Point \( B \) is \( 2.0 \) \( \text{m} \) higher than point \( A \), and the fluid speed at \( B \) is twice the speed at \( A \). If the pressure at \( A \) is \( P_A \), which of the following expressions correctly represents the pressure at \( B \) \( (P_B) \)?

Beginner
Conceptual
GQ

Why are doorknobs located on the side of the door opposite the hinges?

Intermediate
Mathematical
GQ

A car moves at constant speed in a circle of radius 75 m on a horizontal road. The coefficient of static friction is 0.62. Find the maximum speed the car can go without sliding.

Intermediate
Mathematical
GQ

In lacrosse, a typical throw is made by rotating the stick through an angle of roughly \(90^\circ\), then releasing the ball when the stick is vertical, as shown above. If the \(1 \, \text{meter}\) long stick is at rest when horizontal and the ball leaves the stick with a velocity of \(10 \, \text{m/s}\), what angular acceleration must the stick experience?

Intermediate
Conceptual
MCQ

A crate rests on a horizontal surface and a woman pulls on it with a 10-N force. No matter what the orientation of the force, the crate does not move. From least to greatest, rank the normal force on the crate.

Advanced
Mathematical
GQ

A ski lift carries skiers along a \(695 \, \text{m}\) slope inclined at \(34^\circ\). To lift a single rider, it is necessary to move \(72 \, \text{kg}\) of mass to the top of the lift. Under maximum load conditions, five riders per minute arrive at the top. If \(65\%\) of the energy supplied by the motor goes to overcoming friction, what average power must the motor supply?

Beginner
Conceptual
MCQ

A block rests on a frictionless incline. Which statement is correct?

Advanced
Mathematical
GQ

A \(5\)-meter long ladder is leaning against a wall, with the bottom of the ladder \(3\) meters from the wall. The ladder is uniform and has a mass of \(20 \, \text{kg}\). A person of mass \(80 \, \text{kg}\) is standing on the ladder at a distance of \(4\) meters from the bottom of the ladder. What is the force exerted by the wall on the ladder?

Beginner
Conceptual
GQ

Suppose you place a ball in the middle of a wagon, and then accelerate the wagon forward. Describe the motion of the ball relative to the ground. Describe its motion relative to the wagon.

Beginner
Conceptual
GQ

What would your bathroom scale read if you weighed yourself on an inclined plane? Assume the mechanism functions properly, even at an angle.

Intermediate
Mathematical
FRQ

A firecracker in a coconut blows the coconut into three pieces. Two pieces of equal mass fly off south and west, perpendicular to each other, at \( 18 \) \( \text{m/s} \). The third piece has \( 2.5 \) times the mass as the other two.

Intermediate
Conceptual
MCQ

Three identical blocks are being pulled or pushed across a rough horizontal surface by force of identical magnitude F, as shown in the drawing below. Rank the kinetic frictional forces that act on the blocks from smallest to greatest.

Beginner
Mathematical
MCQ

A forward horizontal force of \(12 \, \text{N}\) is used to pull a \(240 \, \text{N}\) crate at constant velocity across a horizontal floor. The coefficient of friction is

Beginner
Mathematical
MCQ

A pendulum has a period of \(2.0 \, \text{s}\) on Earth. What is its length?

Beginner
Mathematical
GQ

Police officers have measured the length of a car’s tire skid marks to be \( 23 \, \text{m} \). This particular car is known to decelerate at a constant \( 7.5 \, \text{m/s}^2 \). What was the car’s initial velocity?

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