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Mangoes
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Homework Statement
"A 1130-kg car is held in place by a light cable on a very smooth (frictionless) ramp. The cable makes an angle of 31 degrees above the surface of the ramp, and the ramp itself rises at 25 degrees above the horizontal.
(a) Find the tension in the cable.
(b) How hard does the surface of the ramp push on the car.
Homework Equations
Newton's laws of motion.
The Attempt at a Solution
The car's in equilibrium, so there is no net force. Two forces are acting on the car: the normal force of the surface and the cable's pull.
I decide to set my x-axis parallel to the surface of the ramp. This means the normal force will be perpendicular to the x-axis and will be go in the direction of the y-axis.
The car has a weight.
Drew a picture:
http://imgur.com/0Bs4rfV
Pretend the car isn't hovering over the ramp.
We know ƩFx = 0
ƩFx = Tcos31 - wcos245 = 0
Tcos31 = wcos245
But weight is (1130 kg)(9.8 m/s^2) = 11074 N
Plugging the value in,
T = (11074*cos245)/cos31 = -3343.76
But this is wrong, T is supposed to be 5460N.
I just can't see where I'm going wrong though.
I haven't done (b) yet, but I figure it would be set up as
normal force + y-component of tension - y component of weight = 0
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