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Question 1.
The device shown is designed to position pieces of luggage on a ramp. It exerts a force parallel to the ramp. The suitcase weighs 200 N. The coefficients of friction between the suitcase and ramp are
s = 0.20 and k = 0.18.

(a) Will the suitcase remain stationary on
the ramp when the device exerts no force on it

(b) What force must the device exert to push the suitcase up the ramp at a constant speed

Question 2.

The coefficient of kinetic friction between the 40-kg crate and the slanting floor is k = 0.3. If the angle
= 20°, what tension must the person exert on the rope to move the crate at constant speed

Question 3.

The mass of the box on the left is 30 kg, and the mass of the box on the right is 40 kg. The coefficient of static friction between each box and the inclined surface is s = 0.2. Determine the minimum angle for with the boxes will remain stationary.

Question 4.

The coefficients of static and kinetic friction between the 100-kg box and the inclined surface are s= 0.45 and k= 0.35. Determine the tension T necessary to pull the box up the surface at a constant rate.

Question 5.

Box 1 sits on a slope inclined at an angle of 30O and box 2 hangs freely. The weights of the two boxes are W1 = 100 N and W2 = 50 N. . The coefficients of static and kinetic friction between box 1 and the inclined surface are = 0.12 and k = 0.10.

(a)For what range of tensions exerted on the rope by the man will the boxes remain stationary

(b)Determine the tension the man must exert on the rope to pull the boxes upward at a constant rate (once the boxes have started moving).

Question 6.

The casting has a mass of 3 Mg. Suspended in a vertical position and initially at rest, it is given an upward acceleration of a = 0.6667 m/s2 . Determine the tension in cables AC and AB during this time interval if the acceleration is constant.

Question 7.

The 160-Mg train travels with a speed of 80 km/h when it starts to climb the slope. If the engine exerts a traction force F of 78,480 N, and the rolling resistance FD is equal to 3139 N, determine the deceleration of the train.

Question 8.

If the motor draws in the cable with an acceleration of 3 m/s2, determine the reactions at the supports A and B. The beam has a uniform mass of 30 kg/m, and the crate has a mass of 200 kg. Neglect the mass of the motor and pulleys.