Stopping distance. A car is traveling on a horizontal road with speed v_0=13.9 m/s at the instant the brakes are locked, so the tires are sliding instead of rolling. Use the work-energy theorem to calculate the minimum distance the car can stop if the coefficient of kinetic friction \mu_k=0.7 between the tires and the road. A: 12 mm B: 16 m C: 17.5 m D; 14 m E: 23.7 m

Computation. A 6.24-kg snake slithers at constant speed all the way around a circular path of radius 2.37 m. The coefficient of friction between the ground and the snake is 0.32. Determine the work done by friction, W, on the body of the snake. Wf J Record your numerical answer below, assuming three significant figures. Remember to include a "if/when necessary. X

4. A 4.7 kg block is pushed 3.1 m up a vertical wall with constant speed by a constant force of magnitude Fapplied at an angle 8=35° with the horizontal, as shown in the Figure. If the coefficient of kinetic friction between block and wall is 0.23, determine a) The work done by F, b) the work done by the force of gravity, c) the work done by the normal force between block and wall. d) By how much does the gravitational potential energy increase during the block's motion? F

A box of mass 4.0 kg hangs by a cable from the ceiling of an elevator. The elevator is moving down at a steady speed of 5.0 m/s for 8.0 m. Use g = 10 m/s2. Match the answers with questions. m v the final kinetic energy of the box (Kf) А. -320 J v the change in kinetic energy of the box (AK) В. 20 J C. 320 J D. 50 J E. -20 J F. -50 J G. OJ

a 40 N horizontal force is applied to a 6.0 kg box. Friction is negligible. The box moves a horizontal distance of 4.0 meters. The work done by the 40 N force is A. 160 J B. 10 J C. 80 J D. 92 J

A force of F= (263 N)E -(125 Nj acts on an objeut, causing a displacement of Āp =(3.15 m) î + (2.81 m) . %3D What is the work done on the object?

A grocery cart with a mass of 10 kg is being pushed at constant speed up a 25° ramp by a force Fp which acts parallel to the incline. (Ignore the friction) a. Draw a free-body diagram of the cart showing all the forces acting on it.  b. Find the work done by each of the forces (W, Fn, Fp) on the cart if the ramp is 7.5 m long.  Hints: The question is very similar to the question of a piano sliding down an incline discussed in class. However, here the object is pushed up the incline. The forces Fn = mgcos(0), and Fp = mgsin(0), so don't spend time getting these using Newton's 2nd law. Also, the weight is W = mg. c. Find the net work done on the cart.

2. An ocean diver swims upwards against the drag force exerted by the water. This force varies in magnitude by depth (d) and is given by F(d)=√d, where y=100 N/m ¹/2. If the diver ascends from a depth of d=10m to the surface (d=0), what is the work done by this drag force? Why is this work negative?

Three objects with masses m, = 6.6 kg, m, = 14 kg, and m3 = 16 kg, respectively, are attached by strings over frictionless pulleys as indicated in the fiqure below. The horizontal surface exerts a force of friction of 30 N on m,. If the system is released from rest, use energy concepts to find the speed of m, after it moves down 4.0 m. m/s m2 m1

1.A brick of mass m initially traveling at speed vo slows to a stop while sliding along a rough horizontal surface. m=7.5 kg, vo=25 m/s a. What is the work done by the frictional force in stopping the brick? b.If the brick slides for 33 m before coming to rest, find μk, the coefficient of kinetic friction between the brick and the surface.   2. A variable force acts on a mass of 1.2 kg as it moves in one dimension along the x-axis.  The force is position-dependent and is given by the equation:  F(x) = (5 N/m) x + 3 N.  Assume there are no other forces acting on the mass.   a. How much work is done by this force in moving the mass from x = 1 m to x = 4 m? b. If the kinetic energy of the mass is 50 J at x = 1 m, what is the kinetic energy of the mass when it reaches x = 4 m? c. What is the velocity of the mass when it reaches x = 4 m?   3. A block of mass m is placed (at rest) against a locked, compressed spring as shown.  The spring has been compressed a distance x from its equilibrium…