Basic Physics Practice Quiz

Rotational inertia, also known as moment of inertia, is the property of an object to resist changes in its rotational motion. It depends on the mass distribution of the object and the axis of rotation. Objects with a higher rotational inertia require more torque to change their rotational motion. This property is important in understanding how objects rotate and how their rotational motion can be affected by external forces.

When a baseball bat is tossed into the air, it wobbles about its center of mass. The center of mass is the point where the mass of an object is concentrated. In the case of a baseball bat, the center of mass is typically located closer to the heavier end of the bat. As the bat rotates in the air, the wobbling motion occurs because the center of mass is not directly aligned with the axis of rotation. This causes the bat to oscillate or wobble around its center of mass.

At point C on the merry-go-round, the tangential speed is initially 0.2 m/s. To double the speed to 0.4 m/s, the rotational speed needs to be increased by a factor of 2. This means that the merry-go-round needs to rotate twice as fast as before, resulting in the increased tangential speed at point C.

When a twirling ice skater brings her arms inward, her rotational speed increases. This is due to the conservation of angular momentum. As the skater pulls her arms closer to her body, her moment of inertia decreases, which causes her angular velocity to increase in order to maintain the same angular momentum. Therefore, her rotational speed increases.

When a torque acts on an object, it tends to produce rotation. Torque is a measure of the force that causes an object to rotate around an axis. It is the product of the force applied and the distance from the axis of rotation. Therefore, the correct answer is rotation, as torque is specifically related to rotational motion rather than linear motion or equilibrium.

By putting a pipe over the end of a wrench, the length of the handle effectively doubles. This increases the leverage and allows for more torque to be applied to the stubborn nut. Since torque is directly proportional to the length of the lever arm, multiplying the length by 2 will result in a multiplication of the torque by 2 as well. Therefore, the correct answer is 2.

As the rotational speed of a merry-go-round increases, the tangential speed also increases. This is because tangential speed is directly proportional to rotational speed. Therefore, if the rotational speed increases by 2, the tangential speed will increase by 2. V = wr will explain the situation.

The correct answer is 1/3 the distance from the fulcrum. This means that the cow is sitting closer to the fulcrum compared to his partner. Since the cow is three times as heavy as his partner, sitting closer to the fulcrum helps balance the weight distribution on the see-saw. If the cow sat further away from the fulcrum, it would create an imbalance and cause the see-saw to tilt towards the cow's side. Therefore, the cow needs to sit 1/3 the distance from the fulcrum to maintain balance.

As you decrease the radius where you apply the force, you will decrease the torque of the wrench. This is because torque is calculated by multiplying the force applied by the perpendicular distance from the axis of rotation. When the radius is decreased, the perpendicular distance decreases, resulting in a decrease in torque.

When one person leans toward the center of the see-saw, their weight is shifted towards that end of the see-saw. This creates an imbalance in the distribution of weight on the see-saw, causing that end to become heavier. As a result, the other end of the see-saw will rise.

Tangential speed is a concept commonly encountered in physics, particularly when dealing with circular motion. When an object moves along the circumference of a circle, its motion can be described in terms of its tangential speed. To understand tangential speed, consider an object moving in a circular path, such as a car driving around a circular track or a planet orbiting around a star. Tangential speed refers to how fast the object moves along the circumference of the circle at any given time. Mathematically, tangential speed is defined as the ratio of the distance traveled along the circular path to the time taken to travel that distance. This can be expressed as Tangential speed = Distance traveled along the circumference / Time taken.

The rotational speed of an object is determined by its angular velocity, which is the rate at which it rotates around a central axis. In this case, the radius of the horses does not affect their rotational speed. The rotational speed depends on factors such as the time taken to complete one rotation or the number of rotations per unit of time. Since the question does not provide any information about the time or the number of rotations, it is not possible to determine which horse has a greater rotational speed. Therefore, the answer is neither.