Suppose a 50kg block slides along a(adsbygoogle = window.adsbygoogle || []).push({});

horizontal surface where the coefficient of kinetic friction

between the block and the surface is uk = 0.60. A force F =

400 N is now applied, where the

angle of the force above horizontal is 20°.

What is the magnitude of the acceleration of the block?

0.54 m/s2

2.31 m/s2

3.27 m/s2

6.78 m/s2

8.11 m/s2

Here's what i did:

F(x-net) = F(applied) - F(friction) = ma

a = F(applied) - F(friction) / m

= (400)(cos 20) - (50 * 9.8 * 0.6) / 50

= 375 N - 294 N / 50 kg

= 1.67 m/s2

I checked my numbers quite a few times and keep getting

1.67, which is not one of the answer choices. The only thing

I saw was that 3.72 m/s2 is exactly double what I got, but I

can't find an explanation for that.

Thanks!

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# Homework Help: Really simple problem - can't get right answer!

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