A contestant in a winter games event pushes a 39.0 kg block of ice across a frozen lake as shown in the figure. 25° The coefficient of static friction is 0.1 and the coefficient of kinetic friction is 0.03. (a) Calculate the minimum force F (in N) he must exert to get the block moving. (b) What is its acceleration (in m/s2) once it starts to move, if that force is maintained? m/s2

A man wants to move a heavy wooden crate (82 kg) across a wooden floor.  However, since he is taller than the crate, he must pull it using a rope that makes an angle of 42 degrees with the horizontal.  He exerts a force of 312 N as he pulls.  What is the Normal Force exerted by the floor on the crate? What is the size of the Friction Force felt by the crate, if the crate moves at a constant speed in a straight line? Imagine that instead the floor is more slick, so that the crate feels a friction force half of what you calculated above.  What is the crate’s acceleration?

Consider a wooden ramp angled 31.7 degrees above horizontal. If a 20.3-kg wooden block is given a strong shove up the ramp so that it has an initial velocity of 22.9 m/s, how long (in seconds) will it take the block to reach its maximum height (before it starts sliding down)? The coefficient of kinetic friction between the block and the ramp is 0.402.

A ball with mass 0.85 kg is thrown upward with initial velocity 30 m/s from the roof of a building 40 m high. Assume there is a force due to v² directed opposite to the velocity, air resistance of magnitude 1325 where the velocity v is measured in m/s. NOTE: Use g=9.8 m/s² as the acceleration due to gravity. Round your answers to 2 decimal places. a) Find the maximum height above the ground that the ball reaches. Height: m b) Find the time that the ball hits the ground. Time: seconds c) Use a graphing utility to plot the graphs of velocity and position versus time.

A robot pushes a 20-kg box on the horizontal surface as part of the moving job. The force is 35 N to the left shown, and the box does not move. The coefficients of friction between the floor and box are µs = 0.75 and uk = 0.40. What is the minimum pushing force (magnitude only) needed to move the box, in Newtons? Useg = 10 m/s². Your answer needs to have 2 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement.

(a) What is the coefficient of kinetic friction between the crate and the floor? (Enter your answer to at least three decimal places.) (b) If the 250-N force is instead pulling the block at an angle of 20.0° above the horizontal, as shown in the figure b, what will be the acceleration of the crate? Assume that the coefficient of friction is the same as that found in part (a). m/s2

Two muscles in the back of the leg pull upward on the Achilles tendon, as shown in the figure. (These muscles are called the medial and lateral heads of the gastrocnemius muscle.) Find the magnitude, in newtons, of the total force on the Achilles tendon.

A 7.62-kg box is pulled along a horizontal surface by a 75.8-N force applied at a 15.1 degree angle above the horizontal. The coefficient of kinetic friction between the box and the surface is 0.209. Calculate the acceleration (in m/s2).

A 55.0 kg block is pulled along a frictionless surface with a force P, exerted at an angle of 25.0 ̊ above the horizontal. What is the minimum force P that will lift the block off the ground? If the block is pulled with half of this force, what will its acceleration be?

At Ted's request, Bill pushes the pizza box across the granite countertop towards Ted. When the box leaves Bill's hand it is sliding at 2.60 m/s. The box comes to rest over a distance of 110 cm. What is the coefficient of kinetic friction, uk, between the pizza box and the countertop? (Ignore air drag.)