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Intermediate
Mathematical
FRQ

A system consists of two small disks, of masses \( m \) and \( 2m \), attached to a rod of negligible mass of length \( 3l \) as shown above. The rod is free to turn about a vertical axis through point \( P \). The two disks rest on a rough horizontal surface; the coefficient of friction between the disks and the surface is \( \mu \). At time \( t = 0 \), the rod has an initial counterclockwise angular velocity \( \omega_0 \) about \( P \). The system is gradually brought to rest by friction. Develop expressions for the following quantities in terms of \( \mu \), \( m \), \( l \), \( g \), and \( \omega_0 \).

Intermediate
Mathematical
FRQ

A car is driving to the right at \( 20 \) \( \text{m/s} \). A motorcycle starts \( 30 \) \( \text{m} \) behind the car and is moving at \( 30 \) \( \text{m/s} \) in the same direction.

Intermediate
Mathematical
FRQ

An adult exerts a horizontal force on a swing that is suspended by a rope of length \( L \), holding it at an angle \( \theta \) with the vertical. The child in the swing has a weight \( W \) and dimensions that are negligible. In terms of \( W \) and \( \theta \), determine:

Intermediate
Mathematical
FRQ

A sample of an unknown material appears to weigh \( 285 \) \( \text{N} \) in air and \( 195 \) \( \text{N} \) when immersed in alcohol of specific gravity \( 0.700 \).

Beginner
Conceptual
MCQ

Late one morning, a mosquito collides with the windshield of a speeding truck. The force of the truck on the mosquito is ____ the force of the mosquito on the truck; the resulting acceleration of the mosquito is ____ the acceleration of the truck.

Intermediate
Conceptual
MCQ

Which of the following graphs shows runners moving at the same speed? Assume the \(y\)-axis is measured in meters and the \(x\)-axis is measured in seconds.

Beginner
Conceptual
GQ

Can an object have \( 0 \) velocity and nonzero acceleration at the same time? Give two examples.

Intermediate
Mathematical
MCQ

A uniform, rigid rod of length \( 2 \) \( \text{m} \) lies on a horizontal surface. One end of the rod can pivot about an axis that is perpendicular to the rod and along the plane of the page. A \( 10 \) \( \text{N} \) force is applied to the rod at its midpoint at an angle of \( 37^{\circ} \). A second force \( F \) is applied to the free end of the rod so that the rod remains at rest, as shown in the figure. The magnitude of the torque produced by force \( F \) is most nearly

Intermediate
Mathematical
MCQ

A \(0.10 \, \text{kg}\) ball, traveling horizontally at \(25 \, \text{m/s}\), strikes a wall and rebounds at \(19 \, \text{m/s}\). What is the magnitude of the change in the momentum of the ball during the rebound?

Advanced
Mathematical
GQ

The graph above shows velocity \( v \) versus time \( t \) for an object in linear motion. Which of the following is a possible graph of position (\( x \)) versus time (\( t \)) for this object?

Intermediate
Conceptual
MCQ

Which statements are not valid for a projectile? Take up as positive.

Intermediate
Conceptual
MCQ

Three identical reservoirs, \(A\), \(B\), and \(C\), are represented above, each with a small pipe where water exits horizontally. The pipes are set at the same height above a pool of water. The water in the reservoirs is kept at the levels shown. Which of the following correctly ranks the horizontal distances \( d \) that the streams of water travel before hitting the surface of the pool?

Beginner
Conceptual
MCQ

During lunch, Alex and Jordan argue about inertia. Alex says if she spins a basketball faster, it will have greater inertia. Jordan argues that inertia only depends on the ball’s mass, not its speed. Who is correct?

Advanced
Conceptual
GQ

Why is the stopping distance of a truck much shorter than for a train going the same speed? Hint: try deriving a formula or stopping distance.

Beginner
Mathematical
GQ

A spring with spring constant \( k = 2.3 \) \( \text{N/m} \) is attached to an object of mass \( 10 \) \( \text{kg} \). If the object is hung from the ceiling by this spring, how much would the spring be stretched?

Advanced
Mathematical
FRQ

A ball of mass \(m\) is released from rest at a distance \(h\) above a frictionless plane inclined at an angle of \(45^\circ\) to the horizontal as shown above. The ball bounces horizontally off the plane at point \(P_1\) with the same speed with which it struck the plane and strikes the plane again at point \(P_2\). In terms of \(g\) and \(h\), determine each of the following quantities:

Intermediate
Mathematical
GQ

A \(25 \, \text{g}\) steel ball is attached to the top of a \(24 \, \text{cm}\)-diameter vertical wheel of negligible mass. Starting from rest, the wheel accelerates at \(470 \, \text{rad/s}^2\). The ball is released after \(\frac{3}{4}\) of a revolution. How high does it go above the center of the wheel?

Advanced
Mathematical
GQ

A boy is sitting at a distance \( d_1 \) from the fulcrum, and girl is sitting at a distance \( d_2 \) from the fulcrum, with \( d_1 > d_2 \). The seesaw is level, with the two ends at the same height. Derive an equation for the minimum mass of the seesaw that will keep it balanced with the two children on it.

Advanced
Mathematical
MCQ

A crate is pulled 2.5 m at constant velocity along a 25° incline. The coefficient of kinetic friction between the crate and the plane is 0.250. What is the efficiency of this procedure?

Advanced
Mathematical
GQ

A \( 35 \) \( \text{kg} \) suitcase rests on a luggage‑loading ramp inclined \( 30.0^\circ \) above the horizontal. To keep it from sliding, a baggage‑handler pushes straight into the ramp (perpendicular to the surface) with a force of \( 45 \) \( \text{N} \). Find the coefficient of static friction \( \mu_s \) between the suitcase and the ramp.

Intermediate
Mathematical
FRQ

A geologist suspects that her rock specimen is hollow, so she weighs the specimen in both air and water. When completely submerged, the rock weighs twice as much in air as it does in water.

Beginner
Conceptual
FRQ

When a golf ball is dropped to the pavement, it bounces back up.

Intermediate
Mathematical
FRQ

Wile E. Coyote is (still) chasing after his arch-nemesis, the Roadrunner across a cliff that is \(125 \, \text{m}\) high. The Coyote is running in the horizontal direction towards the edge of a cliff when, at the last second, the Roadrunner steps out of the way and the witless coyote falls to the canyon floor.

Advanced
Mathematical
MCQ

An astronaut initially at rest in space throws a wrench, and recoils in the opposite direction. Select all that is true.

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