Annie's Wagon: Dragging a Crate with 1200 N of Friction

[starprincess]

Homework Statement

Annie uses her 1.50 x10⁴ N Subaru wagon to drag a 2.00 x 10³ N crate of mulch from the nd of her driveway. She uses a rope to attach the crate to the rear bumper of her wagon and she configures this connection so that her car will exert a horizontal force on the crate. She then gets into her car and accelerates it (and the crate) forward a steady rate of 2.00 m/s². While Annie is thus dragging the crate along her driveway, a steady 1200 N frictional force acts on the crate, opposing its motion.

Homework Equations

Questions I'm having difficulty are:
1. The magnitude of the overall force which the ground exerts on Annie's car equals _____
(the answer is 1.57 x 10⁴ N)

2. The overall force which the ground exerts on Annie's car is directed _____
(answer is above the positive x direction)

The Attempt at a Solution

1. I would assume I need to add the weight of Annie's car and add that to the weight of the crate both which I get a combined 17000 N. This value does not match the correct answer.
2. I cannot find the answer to #2 until I have found the value for #1. From then on, I do not know how to figure it out.

Please help me! Thanks!

 

[tiny-tim]

hi starprincess!

Annie uses her 1.50 x10⁴ N Subaru wagon to drag a 2.00 x 10³ N crate of mulch from the nd of her driveway. She uses a rope to attach the crate to the rear bumper of her wagon and she configures this connection so that her car will exert a horizontal force on the crate. She then gets into her car and accelerates it (and the crate) forward a steady rate of 2.00 m/s². While Annie is thus dragging the crate along her driveway, a steady 1200 N frictional force acts on the crate, opposing its motion.
…
1. The magnitude of the overall force which the ground exerts on Annie's car equals _____
(the answer is 1.57 x 10⁴ N)
…
1. I would assume I need to add the weight of Annie's car and add that to the weight of the crate both which I get a combined 17000 N. This value does not match the correct answer.

No, the weight of the crate has nothing to do with the force which the ground exerts on Annie's car … try the vertical component again.

For the horizontal component, use good ol' Newton's second law for the car-and-crate combined …

what do you get? ​