Physics question. Please help!!!?

Question

I understand what the following question is trying to say, but I'm not sure how to explain it.

You are helping a friend move furniture. The friend asks you to stand inside the back of a pickup truck to hold a piano because there is no rope available to tie it to the truck. Explain why you should refuse this request. Your answer should show that you understand the reasoning used by Galileo and Newton.

Words such as inertia, mass, etc. should be used. Please help me explain this. Thanks :)

Answer 1

The Baldwin upright piano weighs 167 kg, and it's on wheels. You weigh 87 kg, I will assume.

When the truck begins to move, say it will reach 30 mph in 6 seconds that's 13.4 m/s in 6 seconds. That's an average acceleration of 2.23 m/s^2.

The force required to hold the piano since the wheels negligible resistance is 372 N, or about 84 lb.

Since you have to hold the piano with your arms, which are 1.75 m above your feet, the torque is
1.75*372 or 651 Nm,

Now, keep in mind that you are also accelerating at 2.23 m/s^2, so the force of resistance required at your feet is is
272+194, or 566 N, about 126 lbs., which is also a torque on your body 1.75 m below your arms, equivalent to 990 Nm

You will topple over and the piano will roll out of the truck.

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