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Intermediate
Conceptual
MCQ

The rotating systems, shown in the figure above, differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). What happens if you release the hanging blocks simultaneously from rest?

Beginner
Conceptual
GQ

Are astronauts really “weightless” while in orbit?

Advanced
Mathematical
MCQ

A piece of metal of weight \(W\) is suspended by two identical strings. Each string passes through a pulley and is attached to a block of mass \(m\) . The system is in equilibrium.What must be true for \(m\) such that the two strings attached to the piece of metal are almost horizontal.

Beginner
Conceptual
GQ

A skater glides across the ice at a constant \( 6 \) \( \text{m/s} \). After \( 4 \) \( \text{s} \), friction gradually slows them down until they come to rest in \( 6 \) \( \text{s} \). They pause for \( 2 \) \( \text{s} \), then push off in the opposite direction, steadily gaining speed for \( 5 \) \( \text{s} \). Draw the velocity vs. time graph.

Intermediate
Mathematical
FRQ

A high-speed flywheel in a motor is spinning at \( 500 \) \( \text{rpm} \) when a power failure suddenly occurs. The flywheel has a mass of \( 40 \) \( \text{kg} \) and a diameter of \( 75 \) \( \text{cm} \). The power is off for \( 30 \) \( \text{s} \) and during this time the flywheel slows due to friction in its axle bearings. During this time the flywheel makes \( 200 \) complete revolutions.

Intermediate
Conceptual
MCQ

Which of the following best explains why astronauts experience weightlessness while orbiting the earth?

Beginner
Mathematical
MCQ

An old record player could bring a disk up to its \(45\) RPM speed in less than a second. If the same size disk can also be brought up to a speed of \(75\) RPM in about the same amount of time on another player. Compare the torques exerted by each record player.

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?

Intermediate
Mathematical
GQ

A ball is attached to the end of a string. It is swung in a vertical circle of radius \( 2.5 \) \( \text{m} \). What is the minimum velocity that the ball must have at the top to make it around the circle?

Intermediate
Conceptual
MCQ

A stone is falling at a constant velocity vertically down a tube filled with oil. Which of the following statements about the energy changes of the stone during its motion are correct?

I. The gain in kinetic energy is less than the loss in gravitational potential energy.

II. The sum of kinetic and gravitational potential energy of the stone is constant.

III. The work done by the force of gravity has the same magnitude as the work done by friction.

Advanced
Mathematical
MCQ

An object is moving to the west at a constant speed. Three forces are exerted on the object. One force is \( 10 \) \( \text{N} \) directed due north, and another is \( 10 \) \( \text{N} \) directed due west. What is the magnitude and direction of the third force if the object is to continue moving to the west at a constant speed?

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