1. The diagram shows a 0.12-kg square block at four positions along a track. The track is frictionless between points A and B. Elsewhere, the coefficient of static friction on the block is 0.26.
Initially, the block is held in place against a spring by a horizontal external force of magnitude 35 N. Then the external force is removed, and the block is projected forward with speed V1=1.2m/s . The block descends a ramp and has speed V2=1.4m/s at the bottom. At point C, its speed is V3=1.4m/s. The block stops at point D.
What is the initial compression of the spring?
0.99 cm
0.49 cm
0.26 cm
0.67 cm
0.18 cm
2. A 1200-kg car is traveling at 15km/h. A 2400kgtruck has 41 times the kinetic energy of the car. How fast is the truck moving?
68 km/h
82 km/h
54 km/h
96 km/h
3. As a marble rolls across the floor, it gradually slows to a stop due to friction. Which statement best describes the change in mechanical energy of this system?
Mechanical energy was transferred from the floor to the marble.
Mechanical energy was transferred from the marble to the floor.
The mechanical energy of the marble was transformed into nonmechanical energy.
The total energy of the marble and floor, including the mechanical energy, was reduced to zero.
4. A force is applied to an object in a direction that is perpendicular to the object's displacement. The work performed by the force on the object is ______.
negative
positive
zero
5. A slithering snake travels once around a circle of radius 3.20m. The coefficient of friction between the ground and the snake is 0.25, and the snake's weight is 80.0N. How much work does the snake do against friction?
800 J
400 J
3900 J
0 J
6. A car of mass 1091 kg climbs a 5.0A?° slope at a constant speed of 80.0km/h Assuming that air resistance and friction with the road may be neglected, at what rate must the engine deliver mechanical energy to the car?
21 kW
31 kW
39 kW
238 kW
7. A ball is released out a window that is 43 m above the ground. At what speed will it hit the ground? Assume air resistance is negligible.
0.86 km/s
0 m/s
58 m/s
29 m/s
8. A glider with mass m = 0.200 kg sits on a frictionless, horizontal air track. It is connected to a spring of negligible mass and force constant k = 5.00 N/m. You pull on the glider to stretch the spring 0.100 m, and then release the glider. The glider begins to move back toward the equilibrium position (x = 0). What is its speed when x = 0.0800 m?
0.025 m/s
0.300 m/s
0.400 m/s
0.016 m/s
9. A ramp has the shape of one-fourth of a circle of radius R = 3.00 m. A skateboarder begins at rest at the top of the ramp, then rides to the bottom. What is the skateboarder's speed at the bottom of the ramp? Assume that the effect of friction and other nonconservative forces is negligible.
2.45 m/s
7.67 m/s
9.39 m/s
8.33 m/s
10. A total of 87 J of work is needed to stretch a spring from x =1.4m to x =2.9m , in which x is displacement from equilibrium. What is the value of the spring constant?
27 N/m
39 N/m
52 N/m
77 N/m.