a constant horizontal force is applied to block A, which pushes against block B with a 20.0 N force directed horizontally to the right. In Fig. 5-51b, the same force is applied to block B; now block A pushes on block B with a 10.0 N force directed horizontally to the left. The blocks have a combined mass of 12.0 kg. What are the magnitudes of (a) their acceleration in Fig. 5-51a and (b) force ? A B (a) BA (6)

An initially stationary box of sand is to be pulled across a floor by means of a cable in which the tension should not exceed 852 N. The coefficient of static friction between the box and the floor is 0.490. (a) What should be the angle between the cable and the horizontal in order to pull the greatest possible amount of sand, and (b) what is the weight of the sand and box in that situation? (a) Number i Units (b) Number i Units

Two boxes of mass m, =3.9 kg and m,=2.3 kg are made of different materials. The boxes in contact are pushed up an incline of angle 0 = 28" by a force applied to the mass m, of magnitude F=76 N. If the coefficient of kinetic friction between the surface of the incline and the mass m, is Hr. =0.25 and between the surface of the incline and the mass m, is Hk=0.1. m2 a) Determine the magnitude acceleration of both boxes (Hint: The combined object of the masses experiences the applied force, the kinetic friction force of mass m,and m, and the component of the gravitational force downhill) a = b) Determine the magnitude of the contact forces F12 = F21=

Logs weighing 1.3 kg and 2.2 kg lie on a flat surface and are connected by a rope that breaks at a force of 20 N. The coefficient of friction between the lighter log and the base is 0.50, and between the heavier log and the base 0.30. With what maximum force can we pull the lighter log so that the string does not break?

An initially stationary box of sand is to be pulled across a floor by means of a cable in which the tension should not exceed 924 N. The coefficient of static friction between the box and the floor is 0.490. (a) What should be the angle between the cable and the horizontal in order to pull the greatest possible amount of sand, and (b) what is the weight of the sand and box in that situation? (a) Number i Units (b) Number i Units

An initially stationary box of sand is to be pulled across a floor by means of a cable in which the tension should not exceed 1230 N. The coefficient of static friction between the box and the floor is 0.310. (a) What should be the angle between the cable and the horizontal in order to pull the greatest possible amount of sand, and (b) what is the weight of the sand and box in that situation? (a) Number i Units (b) Number i Units > >

27 Go Body A in Fig. 6-33 weighs 102 N, and body B weighs 32 N. The coefficients of friction between A and the incline are 0.56 and P = 0.25. Angle 0 is 40°. Let the positive direction of an x axis be up, the incline. In unit-vector notation. what is the acceleration of A if A is initially (a) at rest. (b) moving up the incline, and (c) moving down the incline? 0 Frictionless, massle pulley Figure 6-33 Problems 27 and 28.

A car traveling at 43 km/h hits a bridge abutment. A passenger in the car moves forward a distance of 51 cm (with respect to the road) while being brought to rest by an inflated air bag. What magnitude of force (assumed constant) acts on the passenger's upper torso, which has a mass of 37 kg? Number Units

A small block of mass 15 kg lies on top of a 34 kg wedge which has a slope of 40°. Find the magnitude of the horizontal force F for which the block does not slip either up or down along the wedge. All surfaces are frictionless.

If the coefficient of friction between a 40.0 kg crate and the floor is 0.680, (a) what horizontal force must a worker exert to just start the motion of the crate? (b) If the worker maintains that force once the crater starts to move and the coefficient of kinetic friction between the surfaces is 0.500, what would happen to the crate?