Car on ramp Answer all parts, check units and tell me if the answers are right.

Question

Car on ramp

Answer all parts, check units and tell me if the answers are right.

QUE STION 1 A A 1535 kg car is moving down a road with a slope grade of 10% at a constant speed of 13 m/s. What is the direction and magnitude of the frictional torce? (define positive in the forward direction, i.e., down the slope)? 9,768.78N B A 1.576 kg car is moving down a road with a slope grade of 11% while slowing down at a rate of 3 m s 2. hat is he direction and magnitude of th mo afro (define positive in the forward direction, i.e., down the slope)? -6,541N A 1 729 kg car is moving down a road with a slope grade o 23% while speeding up at a rate of 1.9 m/s 2. What is the d ection and magnitude of the frictional force? define positive in the forward direction, i.e., down the slope)? c. D. A 1952 kg car is moving down a road with a slope grade of 10% while speeding up at a rate of 3.2 m/s 2. What is the direction and magnitude of the frictional force? (define positive in the forward direction, i.e., down the slope)? 4,342.93N 4,342 93

Explanation / Answer

Part D
as grade is the change in altitude over the length of run
the angle of the slope is

tan = 0.10
= 5.711°

The component of gravity acceleration acting parallel to the slope is
a = gsin
a = 9.81sin5.711
a =0.976 m/s²

so friction from the road on the tires must provide the additional acceleration of
3.2 - 0.976 = 2.224 m/s²

F = ma
F = 1952(2.224)
F = 4342 N downslope

Part A
We don't get to see everything you did so you may have to spot your mistake yourself.

Frictional force is negative and of magnitude F = 1535 × 9.81 × 0.10 = 1506 N.

Note that in mathematics gradient = tangent of the slope's angle to the horizontal; whereas on maps and road signs the gradient = sine of the slope's angle to the horizontal. In this case I would be inclined to say that the given gradient is already the sine of the angle and can therefore be entered directly into the calculation (as above).

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