# What formula do I use?

1. Sep 15, 2005

### wr1015

What formula do I use???

A shopper pushes a 7.3 kg shopping cart up a 13° incline, as shown in Figure 5-21. Find the horizontal force, F, needed to give the cart an acceleration of 1.63 m/s2.

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2. Sep 15, 2005

### Tide

Use $$\vec F = m \vec a$$

3. Sep 15, 2005

### wr1015

i did that and got 18.99 N but its being counted as wrong. There are some formulas in my book that show horizontal force as $$\sum\\F_{x}=F_{1},_{x}+F_{2},_{x}=F_{1}+F_{2}\cos\theta$$ but am not given any forces??

Last edited: Sep 15, 2005
4. Sep 16, 2005

### Tide

You know what the force of gravity is! It's direction is vertical but has a component parallel to the incline. The shopper applies a horizontal force which also has a component parallel to the incline. The sum of the forces parallel to the incline equals mass times acceleration along the incline.

You should be able to take it from there.