SAMPLE EXAM FOR 2-Dimensional motion
and Newton’s Laws of Motion (CH's 3,4)
1] Let East represent the positive x
axis and North
the positive y axis. A constant wind with a speed of 10.0 km/hr is
blowing due
NE. You have a model airplane that flies at 30.0 km/hr in level flight
in still
air. You start its engine and release it in the direction due NW. What
will be
the displacement of the airplane relative to your position after it
flies for
10.0 minutes?
ANSW: 5.26 km @ 117 degrees
2] Assume the motion of a kicked football follows that of a
projectile above
the surface of the earth. The ball is kicked from directly in
front of
the goalpost and hits the crossbar. If the ball was kicked from 20.0 m
away
with a velocity of 15.0 m/s at an angle of 45 degrees to the
horizontal, what
is the height of the crossbar?
ANSW: 2.53 m
3] A block of mass 2.0 kg is observed to slide down an incline at a
constant
velocity when the incline makes an angle of 30 degrees with the
horizontal.
What is the coefficient of kinetic friction between the block and
incline?
ANSW: 0.58
3B] EXPLAIN
BRIEFLY which one of
4] A mass of 0.50 kg is hanging vertically by a string. It is
known that
the string will break if the tension in it exceeds 25 N. What is the
maximum
acceleration that can be given to the mass by pulling up on the string?
ANSW: 40 m/s/s
Describe the condition(s) that would be required for the tension in
the
string to be equal to zero.
1] A plane is flying directly over ETSU at the moment
you begin
this exam. The pilot is heading due West at 500 km/hr, but he is flying
in a 60
km/hr wind that is blowing due South. Where will the plane be (with
respect to
ETSU) when the exam period is over 80 minutes from
now.
ANSW: 672 km @ 6.8 degrees SW
2] Assume the flight of a baseball follows that of a projectile above the surface of the Earth. You are the batter and hit a low pitched baseball that lands at the top of an outfield wall 85.0 meters away. If you gave the baseball a velocity of 30.0 m/s at an angle of 40.0 degrees to the horizontal, what is the velocity of the ball when it strikes the top of the wall? (ignore the initial height of the ball when you hit it)
ANSW: 28.6 m/s @ 36.5 degrees below
horizontal
4] You watch the following events happen while standing on
the shore.
Two sailing ships are passing your location. As you watch ship #1 pass
by,
moving at constant velocity, a stone is dropped from a tall mast of the
ship
and lands on its deck. Ship #2 passes by, moving with a constant
acceleration,
and a stone is also dropped from a tall mast landing on its deck.
EXPLAIN, with
reference to the appropriate laws of motion, where each stone (#1 and
#2) lands
relative to the mast from which it fell. {i.e., do they land at the
foot of the
mast or behind it?}
5] You are pulling a small child on a snow sled up a slope that makes a 30 degree angle with the horizontal . The combined mass of the child and sled is 20.0 kg. It is known that the coefficient of kinetic friction between the snow and sled is m k = 0.130 . If you pull the rope such that a constant force of 125 N is acting on the sled parallel to the surface of the slope, what is the acceleration of the sled/child combination up the incline?
ANSW: +.245 m/s/s
ANSWERS
1) a
2) d
3) c
4) d
5) b
6) c