Exam 3: Forces

You push a chair across the floor and it moves with a constant velocity. Which of the following statements is true for the force of friction?

Two identical spheres are resting on a horizontal surface at a distance of 0.01 m from each other, each attached to an identical unstretched spring with a spring constant of 100 N/m. If we charge the spheres with a negative charge of -1.60 µC each, what is the compression of each spring? Coulomb's constant is k = 9.0 × 10⁹ N m²/C².

Viscous force in a fluid is what is called drag in the air.

A 6 kg box on a 30° incline is held parallel to the incline by a spring attached to the wall. The box is NOT moving. What is the extension of the spring if the spring constant is 100 N/m?

For two bodies gravitationally interacting with each other, if you double each mass and halve the distance between them, by how much would the gravitational force change?

A 50 kg skier is pulled up a 28° slope at a constant speed by a friend applying a force of 300 N. What is the coefficient of kinetic friction between the snow and the skier?

Which one is stronger, the gravitational force with which you attract Earth or the gravitational force that Earth exerts on you?

The surface tension of water makes it possible for certain insects to walk on the surface of water. What is the origin of surface tension?

Some bodies in our solar system are listed in Table 3.1, with masses and radii. -Based on the data in Table 3.1, what is the mass of an object on Jupiter, when its measured weight on Earth is 21 N?

If you are trying to push a crate along a rough floor and it does not move, there is static friction acting between the floor and the crate. The magnitude of static friction is always larger than the applied force; therefore, the object does not move.

If the weight of a chest is 560 N, and you try to push it along the floor with a force of 295 N, and the coefficient of static friction between the floor and the chest is µ = 0.5, will the chest move?

From the data for Earth and the Moon in Table 3.2, how many times stronger is Earth's gravitational field than the Moon's?

You are standing on the floor, not moving. This means that there is no gravity acting on you.

Which of these forces is the weakest of all fundamental forces?

Gravity on the Moon's surface is less than gravity on Earth's surface. For two identical objects, one on Earth and the other on the Moon, how do the mass and weight compare?

Which of the following statements is correct for the force of static friction between two surfaces?

The gravitational force with which Earth attracts you is larger than the force with which you attract Earth.

You drop two iron marbles into a jar of honey. The area of the larger marble is 9 times the area of the smaller one. If the velocity of the smaller marble is half the velocity of the large one, what is the ratio of the viscous forces on the two marbles?

Two identical spheres are resting on a horizontal surface at a distance of 0.04 m from each other, each attached to an identical unstretched spring with a spring constant of 100 N/m. If we charge the spheres with a negative charge of -1.60 ìC each, what is the new spacing between the spheres? Coulomb's constant is k = 9.0 × 10⁹ N m²/C².

A child manages to use his feet to stop and rest on a slide before he starts gliding again. Choose the free body diagram from below that correctly describes the forces acting on the child while he is at rest.