Student "edition" found at {csi dot journalspace dot com}.

Maybe I shouldn't have started this blog now, not with everything that's been going on.

My general science requirement mechanics lecture class’ third exam was yesterday.

I only gave them four problems instead of the usual five or six, but a lot of them still stayed to work on the problems until I gave the signal to pass their papers.

The first question was on the special case of projectile motion where the initial angle is zero and therefore there is only the horizontal component of the initial velocity to deal with.

This was also the one problem in each exam I gave that was in feet, so they either had to convert it to meters or use the acceleration due to gravity in feet per second squared.

The horizontal displacement was also given, from which they could get the time of trajectory, the vertical displacement, and the final velocity and angle.

The second question had one object with horizontal motion, but from two forces that were angled.

They had to get the components of the forces, get the summation of forces, then determine the direction of intended motion to get the direction of the friction.

Unlike the first problem here all they had to find was the acceleration when it starts moving.

In the third problem there is a block on an inclined plane connected by a rope on a pulley to a hanging mass. Unlike our previous examples though, here the plane is frictionless, which made the problem a lot easier.

All that was being asked of them was the range of values for which the block would move up the plane, and would move down the plane. Actually the answer would only be all masses greater than or less than a certain value.

For the smaller range, they could also have the lower bound as any mass greater than zero.

I also asked what the tension on the rope would be if the mass of the block on the inclined plane is given. Actually here the value would be the same as in the previous two scenarios. Someone even asked if they could use the given mass in the previous two scenarios, and I answered no, and would have said yes if the question was reversed.

Session 1559 arrived at almost halftime of the exam, giving doubt to whether the score would be passing. Class dismissed.