Exam 7: Work and Kinetic Energy

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s². What is the work done by the 10 N force on the object along the inclined plane?

FIGURE 7-4 A constant force of 100 N is applied to a mass of 40.0 kg as shown in Figure 7-4. The force causes a displacement of 20.0 m to this mass along the + x-axis. Neglect friction. -What is the work done by the component of the force in Figure 7-4 along the +x-axis?

A man lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building. How much work was done by the man in lifting the bucket?

If the net work done on an object is positive, then the object's kinetic energy

Consider a plot of the displacement (x) vs. applied force (F) for an ideal elastic spring. The slope of the curve would be

A person applies a constant force on an object of mass 20 kg that causes the object to move horizontally at a constant speed of 0.20 m/s through a distance of 0.80 m. What is the work done on the object?

A person applies a constant force of 20 N to a rock of mass 1000 kg, for a total of 20 seconds. What is the work done by this person if the rock does not move at all by this applied force?

Lisa runs up 4 flights of stairs in 22. seconds. She weighs 510. Newtons. If each flight rises 310. cm: (a) What is her change in potential? (b) What average power (watts) was required during the 22. s? (c) What minimum horsepower motor would be required to do this?

FIGURE 7-2 Three applied forces, F₁ = 20.0 N, F₂ = 40.0 N, and F₃ = 10.0 N act on an object with a mass of 2.00 kg which can move along an inclined plane as shown in the figure. The questions refer to the instant when the object has moved 0.600 m along the surface of the inclined plane in the upward direction. Neglect friction and use g = 10.0 m/s². -Refer to Figure 7-2. What is the amount of work done by force F₂ as the object moves up the inclined plane?

Kinetic energy is proportional to mass.

A truck has four times the mass of a car and is moving with twice the speed of the car. If K_t and K_c refer to the kinetic energies of truck and car respectively, it is correct to say that

An object of mass 10.0 kg is released from the top of an inclined plane which makes an angle of inclination of 30.0° with the horizontal. The object slides along the inclined plane. The questions refer to the instant when the object has traveled through a distance of 2.00 m measured along the slope. The coefficient of kinetic friction between the mass and the surface is 0.200. Use g = 10.0 m/s². (a) How much work is done by the net force on the mass? (b) How much work is done by the force of friction?