A 4 kg block is sliding down a vertical wall while being pushed by an external force as shown in the figure. What coefficient of kinetic friction would be required for the block to move down the wall at constant speed if the magnitude of the external force is 30 N? 4 kg F 30° 1.31

A steel beam is suspended from two ropes as it is lifted to the top of a building at a constant speed. One of the ropes makes an angle of 27.1 degrees with respect to the vertical and has a tension of 711 N, while the other makes an angle of 25.7 with respect to the vertical. What is the beam's mass in kg?

m F 0 You are pressing a box against a sloped ceiling, perpendicular to the ceiling itself, as shown in the figure. The mass of the box is m=3.3 kg, the angle of the ceiling is 0=37°, and the coefficients of friction are μs-0.31 and μk=0.2. (a) What is the minimum force needed from you to keep the box at rest? N (b) Choosing up the sloping ceiling to be the positive direction, suppose you push with a force 4 N smaller than your answer to the previous part. What will be the acceleration of the box? m/s²

The figure below shows a bird feeder that weighs 167.9 N. The feeder is supported by a vertical string, which is in turn tied to two strings, each of which is attached to a horizontal branch. The left string makes a 60° angle with the branch, while the right string makes a 30° angle. What is the tension in each string (in N)?   left string __N right string __N bottom string __N