Mechanics | Relativity Answers

A roller-coaster car is moving at 20 m/s along a straight horizontal track. What will its speed be after climbing the 15-m hill shown in the figure, if friction is ignored?

http://edugen.wileyplus.com/edugen/courses/crs3976/art/qb/qu/c06/q40-1.png

A helicopter (m = 3250 kg) is cruising at a speed of 56.9 m/s at an altitude of 185 m. What is the total mechanical energy of the helicopter?

A warehouse worker uses a forklift to raise a crate of pickles on a platform to a height 2.75 m above the floor. The combined mass of the platform and the crate is 207 kg. If the power expended by the forklift is 1440 W, how long does it take to lift the crate?

What power is needed to lift a 49-kg person a vertical distance of 5.0 m in 20.0 s?

The kinetic energy of a car is 8 × 106 J as it travels along a horizontal road. How much power is required to stop the car in 10 s?

A 325-N force accelerates a 50.0-kg crate from rest along a horizontal frictionless surface for a distance of 20.0 m as shown in the figure.

http://edugen.wileyplus.com/edugen/courses/crs3976/art/qb/qu/c06/r7-1.png

What is the final speed of the crate?

Consult Multiple-Concept Example 5 for insight into solving this problem. A skier slides horizontally along the snow for a distance of 14.7 m before coming to rest. The coefficient of kinetic friction between the skier and the snow is 0.0376. Initially, how fast was the skier going?

A 1590-kg car is being driven up a 6.58 ° hill. The frictional force is directed opposite to the motion of the car and has a magnitude of 529 N. A force F is applied to the car by the road and propels the car forward. In addition to these two forces, two other forces act on the car: its weight W and the normal force FN directed perpendicular to the road surface. The length of the road up the hill is 243 m. What should be the magnitude of F, so that the net work done by all the forces acting on the car is 187 kJ?

A 255 N force is pulling an 94.6-kg refrigerator across a horizontal surface. The force acts at an angle of 16.7 ° above the surface. The coefficient of kinetic friction is 0.173, and the refrigerator moves a distance of 5.88 m. Find (a) the work done by the pulling force, and (b) the work done by the kinetic frictional force.

A 72.0-kg man is riding an escalator in a shopping mall. The escalator moves the man at a constant velocity from ground level to the floor above, a vertical height of 5.20 m. What is the work done on the man by (a) the gravitational force and (b) the escalator?