Asked Jan 27, 2020

Hi, I don't know if I was given enough or have too much uneccesary information to solve this problem, but here it is.

An 80 kg guy is running on a flat surface at a velocity of 10 m/s.  He gets on a 4 kg skateboard that is sitting at rest at the top of a 45-degree inclined plane (see drawing).  If the time taken to travel from point A to point B is 6 seconds and only gravitational acceleration is acting on the guy/skateboard unit, find

a) the velocity of the unit when t = 3 seconds;

b) the height h at point A.

I'm also not sure which part should be solved first.  Thanks.

M= 80kg
VE10 m/s

Image Transcriptionclose

M= 80kg M3D VE10 m/s .A m=4kg' V.D0 45


Expert Answer

Step 1

First, apply momentum conservation, and solve for the velocity of the unit at point A along horizontal direction vH.

Physics homework question answer, step 1, image 1
Step 2

Now consider the diagram for the velocity and acceleration along the incline, that is the direction of motion from point A to point B. The component of the velocity vH along the incline will be the initial velocity of unit for the motion between the point A and B.

Physics homework question answer, step 2, image 1
Step 3



From the diagram, use equation of motion, and solve for the veloc...

Physics homework question answer, step 3, image 1

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