Name (please print):___________________________________________ Total Points:_____
(last) (first)
4. [20 points] A physics student observes the motion of an insect gliding on the surface of a pond and
correctly draws the trajectory of the insect as shown in the top-view diagram. The insect started from
rest at point A. Near point C the insect is moving in a straight line.
At certain labeled points (A-F) along the trajectory,
the student has also indicated the directions of the
velocity and acceleration vectors of the insect that
may or may not be correct.
A. [15pts] For each of the points A-E only, state
in the table below whether the directions of the
vectors the student has drawn can or cannot be
correct (assuming a correct trajectory).
For each case that cannot be correct:
• explain why the direction of the arrows
cannot be correct, and
• draw a correct vector on the diagram.
Point Can be correct
direction for
velocity? (Y/N)
Can be correct
direction for
acceleration? (Y/N)
If either direction cannot be correct, explain.
A
B
C
D
E
B. [5pts] The student has shown the correct directions of the velocity and acceleration at point F.
Was the speed of the insect increasing, decreasing, or neither at point F? Explain your reasoning.
a
a
a
a
a
a = 0
= 0v v
v
v
v
v
B
CD
E
F
A
directions only!
TOP VIEW