wall A block of mass m = 2 kg is held stationary against a wall by applying a horizontal force F on it as shown in Fig. 5.41. If the coefficient of fric- m F- tion between the block and the wall is u = 0.25, find the minimum value of F required to hold the block against the wall. Take g = 10 ms2. %3D Fig. 5.41

A crate remains stationary after it has been placed on a ramp inclined at an angle with the horizontal. Which of the following statements must be true about the magnitude of the frictional force that acts on the crate? O It is least equal to the weight of the crate. O It is equal to n. O It is larger than the weight of the crate. O It is greater than the component of the gravitational force acting down the ramp. O It is equal to the component of the gravitational force acting down the ramp.

1O C A cart for hauling ore out of a gold mine has a mass of 439 kg , including its load. The cart runs along a straight stretch of B Track track that climbs a shallow 4.75° incline. A donkey, which is Rope trudging along and to the side of the track, has the unenviable job of pulling the cart up the slope with a 441 N force for a distance of 185 m by means of a rope that is parallel to the slope but makes an angle of 14.5° with the track. A „Track incline Model the rolling resistance of the cart as though it were Horizontal ground sliding on the track with a coefficient of friction of 0.0163. Use g = 9.81 m/s, and note that angle A in the image is the angle of the incline while angle B is the angle the rope makes %3D with the track. Find the work Wa that the donkey performs on the cart during this process. %3D Find the work W, that the force of gravity performs on the cart during this process. = "M Calculate the work W done on the cart by friction during this process. 87