Q1. Objects with masses m1 = 11.0 kg and m2 = 8.0 kg are connected by a light string that passes over a frictionless pulley as in the figure below. If, when the system starts from rest, m2 falls 1.00 m in 1.34 s, determine the coefficient of kinetic friction between m1 and the table.
Q2. A car is traveling at 46.0 km/h on a flat highway.
(a) If the coefficient of friction between road and tires on a rainy day is 0.113, what is the minimum distance in which the car will stop?
(b) What is the stopping distance when the surface is dry and the coefficient of friction is 0.565?
Q3. A football punter accelerates a football from rest to a speed of 14 m/s during the time in which his toe is in contact with the ball (about 0.30 s). If the football has a mass of 0.46 kg, what average force does the punter exert on the ball?
Q4. A 78-kg man standing on a scale in an elevator notes that as the elevator rises, the scale reads 827 N. What is the acceleration of the elevator?
Q5. A 4.8-g bullet leaves the muzzle of a rifle with a speed of 338 m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the 0.84-m-long barrel of the rifle?
Q6. 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, a 13,000-kg load sits on the flatbed of a 20,000-kg truck moving at 10.0 m/s. Assume the load is not tied down to the truck and has a coefficient of static friction of 0.650 with the truck bed.
(a) Calculate the minimum stopping distance for which the load will not slide forward relative to the truck.
(b) Is any piece of data unnecessary for the solution? (Select all that apply.)
Q7. A dockworker loading crates on a ship finds that a 28-kg crate, initially at rest on a horizontal surface, requires a 70-N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 54 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor.
Q8. The coefficient of static friction between the m = 2.65-kg crate and the 35.0° incline of the figure below is 0.320. What minimum force F must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline?
