An Intro to ^{nd}

1) The
mass of an old brown dog is 19.0 kg. What is his weight, in

2) A 0.70
kg squirrel falls from a tree. Poor squirrel. Gravity pulls it downwards with a
force of 6.9 N, and air resistance creates an upwards force of 1.5 N. What is
its acceleration on the way down?

3) Put
a small child on a tricycle, and then roll him down a hill. The forces
accelerating the little fellow are his weight (pulling him downhill) and
friction (pulling him uphill). He starts at rest, and reaches 18 m/s after 3.3
s. If his mass is 26 kg, what was the *net* force acting on him?

4) Build
a free-body diagram for a 65 kg person standing in an elevator. If the elevator
were accelerating downwards at 1.5 m/s^{2} how hard would the floor be
pushing on the person?

5) Find
the apparent weight of a 65 kg someone accelerating downwards at 9.8 m/s^{2}.

6) A
25 kg box is dragged horizontally by a 75 N force directed 35° above the horizontal.
The ground is frictionless, and the box starts from rest. How fast it will
be moving after being dragged for 4.0 m?

7) Another
25 kg box is dragged by a 75 N force, this time making an angle θ above
the horizontal. The ground is *not*
frictionless; the force of friction equals 57 N. If the box is being dragged
at a constant velocity, find the angle θ.

8) A
skier slides down a frictionless slope. Her mass is 65 kg. If the angle of the
slope is 25° what is her acceleration?

9) Another
skier slides down another slope, but this time the slope is not frictionless.
The skier’s mass is 85 kg, the frictional force is 110 N, and the angle of the
slope is 15°. Find his acceleration.