I have a few questions. Should we be taking Test 1 this week?
You should.
My next question is from the test - A ball of mass 8 kg rolls off the edge of a ramp with a horizontal speed of 70 cm/s. What is the KE as it rolls off the ramp? I worked this question using KE=.5mv^2 and got 1.96 N.
I believe that is correct.
I am not sure how to work the rest of these questions.
How much KE does it gain as it falls 10 cm?
What happens to the ball's PE as it falls 10 cm?
If you assume that air resistance exerts a negligible force on the ball as it falls, how much work is done by nonconservative forces during the fall? The answer is 0; make sure you understand why.
What therefore happens to its KE?
How much of the ball's KE at this point is accounted for by its horizontal velocity, and how much by its vertical velocity?
Its horizontal velocity hasn't changed. What therefore is its KE in the horizontal direction?
Since v = sqrt(v_x^2 + v_y^2) it follows that 1/2 m v^2 = 1/2 m ( v_x^2 + v_y^2 ) = 1/2 m v_x^2 + 1/2 m v_y^2--i.e., the total KE is equal to the KE in the x direction plus the KE in the y direction.
Thus you know the total KE and you know the KE in the x direction. What therefore is the KE in the y direction?
What then is its vertical velocity at this point?
This is a projectile and I assume we should look at the horizontal and vertical velocities but I don't know where to begin.
If you know its vertical KE then you can find its vertical velocity.