Posts
I said "daily" review, and I sorta mean it - I teach on Saturday mornings, so no reason not to post a fundamentals check today. I'll post number 4 on Monday, though, 'cause even at boarding school we don't teach on Sundays. :-)
FUNDAMENTALS CHECK #3
21. Write the equation for the force of a spring.
22. Write the equation for the potential energy of a spring
23.
On a velocity-time graph, how do you determine
the position of an object?
Questions 24 and 25: A motor cart in the laboratory can be set to move at any steady velocity. A student sets the cart into motion at many different steady velocities, each time measuring the distance the car travels in 5.0 seconds. The student graphs this distance on the vertical axis, and the cart’s velocity on the horizontal axis.
24. Is this graph a line or a curve? Briefly, why?
25. If this graph is a curve, what could be graphed instead to get a straight line? If this graph is a line, what is the physical meaning of the slope?
26. Write the equation for the gravitational field at the surface of a planet.
27. When a planet makes a circular orbit around a sun, say or show briefly how to solve for the planet’s orbital speed.
28. In what kind of collision is mechanical energy conserved?
29. In what kind of collision is linear momentum conserved?
30. Write the equation for kinetic energy.
My answers to fundamentals check 3:
ReplyDelete21. F = kx.
22. SPE = (1/2)kx^2.
23. You can't. (The displacement is the area under the v-t graph, but the position is undeterminable.)
24. Line - the equation for steady speed is d=vt. So d is linear with v - no squares or square roots or denominators.
25. The y-axis is d, the x-axis is v. So what's multiplying the x-axis variable is the slope - that's t. The slope should be the time the cart spent in each trial, i.e. 5 seconds.
26. g = GM/r^2.
27. Set the gravitational force equation equal to ma, where a is v^2/r.
28. elastic.
29. *all* collisions. (Because no external force acts on the two objects in the collision, just the internal force of one object on the other.)
30. KE = (1/2)mv^2
30.