Using Conservation of Mechanical Energy to Calculate the Speed of a Toy Car A 0.100-kg toy car is propelled by a compressed spring, as shown in Figure 7.12. The car follows a track that rises 0.180 m above the starting point. The spring is compressed 4.00 cm and has a force constant of 250.0 N/m.

Assuming work done by friction to be negligible, find 

(a) How fast the car is going before it starts up the slope 

(b) How fast it is going at the top of the slope.

Strategy
The spring force and the gravitational force are conservative forces, so conservation of mechanical energy can be used. Thus,

where is the height (vertical position) and is the compression of the spring. This general statement looks complex but becomes much simpler when we start considering specific situations. First, we must identify the initial and final conditions in a problem; then, we enter them into the last equation to solve for an unknown.

Transcribed Image Text:

mmo Alternate path Path of the Car h = 18 cm.