T. Highways often include so-called truck ramps for semi-trucks whose brakes go
ID: 2034357 • Letter: T
Question
T. Highways often include so-called truck ramps for semi-trucks whose brakes go out while going down a steep incline and hence going very fast. If you have a ramp that's 90 m long and going upward at a 39° angle, what's the fastest a run away truck could be going when it entered the ramp and still stop before the ramp ended? Note that this is the sarne problem as from Hornework #3, but now you can do it with energy instead of using Newton's 2nd Law. You're welcome. 2. A plane with a mass of 290,000 kg is moving upwards at a 12 angle at a constant velocity of 120 m/s. The plane is experiencing a drag force of 105 kN opposite its direction of motion. How much power do the engines of the plane need to generate in order to do this?Explanation / Answer
Given,
L = 90 m ; theta = 39 deg
from conseration of energy
KE = PE
1/2 m v^2 = m g L sin(theta)
v = sqrt (2 g L sin(theta))
v = sqrt (2 x 9.81 x 90 x sin39) = 33.34 m/s
Hence, v = 33.34 m/s
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