1. A1200-N crate is being pushed across a level floor at a constant speed by a force of340N at an angle of 20.0below the horizontal, as shown in the figure below.(a) What is the coefficient of kinetic friction between the crate and the floor? Your response differs from the correct answer by more than 10%. Double-check your calculations. (b) If the 340 N force is instead pulling the block at an angle of 20.0above the horizontal as shown in the figure, what will be the acceleration of the crate? Assume that the coefficient of friction is the same as that found in part (a). The correct answer is not zero.m/s²

2. Consider a large truck carrying a heavy load, such as steel beams. A significant hazard for the driver is that the load may slide forward, crushing the cab, if the truck stops suddenly in an accident or even in braking. Assume, for example, a13,000-kgload sits on the flatbed of a20,000-kgtruck moving at14.0m/s.Assume the load is not tied down to the truck and has a coefficient of static friction of0.600with the truck bed.

(a) Calculate the minimum stopping distance for which the load will not slide forward relative to the truck. m (b) Is any piece of data unnecessary for the solution? (Select all that apply.)

mass of the load mass of the truck velocity coefficient of static friction

3. Calculate the magnitude of the normal force on a17.7kg block in the following circumstances. (Enter your answers in N.)

(a)The block is resting on a level surface. The four cases in this problem are the most common situations. In general, solving for the normal force involves drawing a free-body diagram and applying Newton's second law.N

(b)The block is resting on a surface tilted up at a25.8angle with respect to the horizontal. N

(c)The block is resting on the floor of an elevator that is acceleratingdownwardat5.03m/s². N

(d)The block is on a level surface and a force of145N is exerted on it at an angle of25.8belowthe horizontal. N