1) A 980 kg car is pulling a 315 kg trailer. Together the car and trailer move forward with an acceleration of 2.25 m/s2. Ignore any frictional force of air drag on the car and all frictional forces on the trailer.

(a) Determine the net force on the car.

(b) Determine the net force on the trailer.

(c) Determine the force exerted by the trailer on the car.

(d) Determine the resultant force exerted by the car on the road. (Assume that the forward direction is along the +x-direction.)

2) A bag of cement weighing 250 N hangs in equilibrium from three wires as suggested in the figure below. Two of the wires make angles θ₁ = 64.0° and θ₂ = 45.0° with the horizontal. Assuming the system is in equilibrium, find the tensions T₁, T₂, and T₃ in the wires.

3) Two objects are connected by a light string that passes over a frictionless pulley as shown in the figure below. Assume the incline is frictionless and take m₁ = 2.00 kg, m₂ = 6.90 kg, and θ = 56.5°.

(a) Draw free-body diagrams of both objects.

(b) Find the magnitude of the accelerations of the objects.=m/s2

(c) Find the tension in the string.=N

(d) Find the speed of each object 1.25 s after being released from rest. =     m/s

4) Two blocks, each of mass m = 3.00 kg are hung from the ceiling of an elevator as in the figure below.

(a) If the elevator moves with an upward acceleration  of magnitude 1.5 m/s2, find the tensions T1 and T2 in the upper and lower strings.

(b) If the strings can withstand a maximum tension of 71.9 N, what maximum acceleration can the elevator have before a string breaks?

5) A 8.80-kg hanging object is connected by a light, inextensible cord over a light, frictionless pulley to a 5.00-kg block that is sliding on a flat table. Taking the coefficient of kinetic friction as 0.220, find the tension in the string.

6) A coin placed 30.4 cm from the center of a rotating, horizontal turntable slips when its speed is 49.0 cm/s.

(a) What force causes the centripetal acceleration when the coin is stationary relative to the turntable?(choose)

• static friction
• inertia
• kinetic friction
• centrifugal force

(b) What is the coefficient of static friction between coin and turntable?

7) A 39.0-kg child swings in a swing supported by two chains, each 3.10 m long. The tension in each chain at the lowest point is 352 N.

(a) Find the child's speed at the lowest point.

(b) Find the force exerted by the seat on the child at the lowest point. (Ignore the mass of the seat.)