# I al lost

1. Sep 28, 2005

### physicsidiot71784

I have some questions that I need help answering and are due friday september 30th but i need the help to answer them. ok here goes. The question is What is the difference between motion at constant velocity and motion at constant acceleration? Explain your answer.
I say that there is no difference because motion at constant velocity and constant acceleration is zero. Is that right or is there someway you can help me understand.
The other question is if you have a baseball and a lead ball, that is much heavier, that is falling from the same height as the baseball, and the drag is negligible how would the strobe of the lead be different from the baseball strobe?
My answer to this was they would be the same. Our teacher said something about the weight has nothing to do with it. I am confused because I missed that day of lecture due to a sick kid. can you help me understand?
Another question was if a package is placed in a bed of a pickup truck and it slides towards the back when speeding up and towards the front when slowing down. Which newtons law? apply it directly to the motion and explain why.
I think it is newtons first law but the laws confuse me. I need help explaining the laws to answer this question.

2. Sep 28, 2005

### Andrew Mason

I am not sure what you mean by your answer. Motion at constant velocity (eg. 100 m/sec) is zero?

With constant (non-zero) acceleration, the velocity is continually changing. So if you measure the velocity at different times you will get different velocities. With constant velocity (0 acceleration) the velocity is the same at all times.

This is just Galileo's 'time of fall' experiment. All objects fall with the same acceleration (g).
It demonstrates Newton's first and second laws. The package is not attached to the truck. It is held on the bed by friction. If the truck engine applies force to the truck, the truck accelerates. But the package on the bed can only accelerate at the same rate if the force which the truck is exerting on the package (friction) is sufficient to accelerate the package at the same rate. Otherwise it maintains uniform motion (and the truck accelerates under it).

AM