Calculate the force (in N) needed to bring a 1050 kg car to rest from a speed of 80.0 km/h in a distance of 100 m (a fairly typical distance for a non-panic stop). N (b) Suppose instead the car hits a concrete abutment at full speed and is brought to a stop in 2.00 m. Calculate the force exerted on the car and compare it with the force found in part (a). force in (b) force in (a) =

A man pushing a crate of mass m = 92.0 kg at a speed of  v = 0.880 m/s encounters a rough horizontal surface of length ℓ = 0.65 m as in the figure below. If the coefficient of kinetic friction between the crate and rough surface is 0.354 and he exerts a constant horizontal force of 297 N on the crate.   (a) Find the magnitude and direction of the net force on the crate while it is on the rough surface. magnitude                                                       N direction    (b) Find the net work done on the crate while it is on the rough surface.                                    J(c) Find the speed of the crate when it reaches the end of the rough surface.                                       m/s

A daredevil wishes to bungee-jump from a hot-air balloon 64.5 m above a carnival midway. He will use a piece of uniform elastic cord tied to a harness around his body to stop his fall at a point 12.0 m above the ground. Model his body as a particle and the cord as having negligible mass and a tension force described by Hooke's force law. In a preliminary test, hanging at rest from a 5.00-m length of the cord, the jumper finds that his body weight stretches it by 1.65 m. He will drop from rest at the point where the top end of a longer section of the cord is attached to the stationary balloon. (a) What length of cord should he use? m(b) What maximum acceleration will he experience? m/s2

At the start of a race, a four-man bobsled team pushes their sled as fast as they can along a 50 m flat starting stretch. The net force that the four men together apply to the 325 kg bobsled is 80.093 N directed at 15 degrees below the horizontal. As they push, 60 N of kinetic friction opposes them. What is the speed of the sled right before the team jumps on the sled?

A 86.0 kg diver steps off a 10.0 m high diving board and drops, from rest, straight down into the water. If he comes to rest 7.20 m beneath the surface of the water, determine the average resistive force exerted by the water.

A 18-kg sled is being pulled along the horizontal snow-covered ground by a horizontal force of 24 N. Starting from rest, the sled attains a speed of 1.7 m/s in 9.1 m. Find the coefficient of kinetic friction between the runners of the sled and the snow. Number i Units