A pickup truck has a wheelbase of 3.20 m . Ordinarily, 1.068×104 N rests on the

Question

A pickup truck has a wheelbase of 3.20 m . Ordinarily, 1.068×104 N rests on the front wheels and 8620 N on the rear wheels when the truck is parked on a level road.

A box weighing 3700 N is now placed on the tailgate, 1.00 m behind the rear axle. How much total weight now rests on the front wheels?

9450

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Correct

Part B

On the rear wheels?

1.36×104

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Correct

Part C

How much weight would need to be placed on the tailgate to make the front wheels come off the ground?

For Part C, I got 34,161 N, but Mastering Physcics says it is incorrect.

9450

Explanation / Answer

First find the horizontal position of the truck's CG. By equilibrium of vertical forces, the total weight of the truck is 10680 + 8620 = 19300 N.
The moment around the rear axle is 19300*x - 10680*3.2, where x is the distance from rear axle to CG. The moment must be 0, so x = 1.77 m

For the front wheels to be off the ground, Ff = 0

19300*x - W*1.00 = 0
34161 - W*1.00 = 0
W = 34161 N

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