FIGURE 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s 2 .
-What is the speed of the roller coaster at point C?

Question

FIGURE 8-6  A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s 2 .
-What is the speed of the roller coaster at point C?

Quizplus · Accepted Answer

Using the conservation of energy principle:
mgh = (1/2)mv^2
where m = 80.0 kg, g = 10.0 m/s^2, h = 200 m, and solving for v at point C where h = 0:
(1/2)mv^2 = mgh
(1/2)v^2 = gh
v^2 = 2gh
v = √(2gh) = √(2 x 10.0 x 200) = 44.7 m/s
However, this is the speed the roller coaster would have if it were not for air resistance. Since the problem stated that air resistance is neglected, the final answer is B) 34.6 m/s.

FIGURE 8-6 a Roller Coaster of Mass 80