AP Physics C 2017

(A)         90  m/s

(B)         104 m/s

(C)         156 m/s

(D)         208 m/s

(E)         360 m/s

Questions   3   and 4   refer   to  the following   information: A  fisherman   wishes  to  pilot   his boat    directly

north   across  a   river   to  a   destination marked  by  an  X   on  the figure. The river   has a   westward    current of

3   m/s,    and the boat    can travel  5   m/s in  still   water.  The fisherman   points  his boat    at  a   heading angle   of

θ   into    the current as  shown   and begins  his journey.

3 . What heading angle θ should the fisherman use to travel directly north across the river?

(A)         30°

(B)         31°

(C)         37°

(D)         53°

(E)         59°

4 . What is the boat’s resultant velocity while traveling due north across the river?

(A)         2.0 m/s

(B)         3.0 m/s

(C)         3.8 m/s

(D)         4.0 m/s

(E)         5.8 m/s

Answers

1 . E —Vectors should be added head to tail. Note: Student B simply showed the correct resultant
vector R . Student C chose to break vector P into its x and y components and add them to the vector Q
.

2 . A —The westward component of the velocity is given by the following equation: