The magnetic field of a long, straight, and closely-wound solenoid, inside the solenoid at a point near the center, is 0.920 T. What is the magnitude of the magnetic field at this point if the current in the solenoid is increased by a factor of 2.50?

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Which situation will produce the greatest change of momentum

What is the coefficient of kinetic friction μk between the block and the tabletop?