Practice
for the Multiple-Choice Portion of the AP Exam (and for donuts)
Names:__________________________________________________________________
For each
of the following problems
assume the positive vertical direction is up and the positive horizontal
direction is to the right. All symbols have the usual definitions.
Circle
all correct answers.
¢
A
constant force Fp, acting in the horizontal direction, is pulling
a box of mass m along a
horizontal surface with
a force of friction, Ffr, as shown. The direction of the force is
friction is
not shown – that is for
you to determine. The box starts from rest at point a and is pulled a
distance of d meters to point b.
a. (Fpd
-
Ffr
d)
newtons
b.
Fpdcos(0) -
Ffr
d
cos(180) newtons
c. (Fpd
-
Ffr
d)
joules
correct
d.
Fpdcos(0) -
Ffr
d
cos(180) joules
e.
Fpdcos(0) +
Ffr
d
cos(180) joules
correct
¢
A
constant force Fp, acting in the horizontal direction, is pushing a box of
mass m along a
horizontal surface with
a force of friction, Ffr. The box starts from rest at point b and
is pushed
a distance of d meters
to point a. Note that the above diagram must be modified as
appropriate (for the
calculations only, you do not need to redraw the diagram).
The net
work done on the box is:
a. (Fpd
+
Ffr
d)
newtons
b.
-Fpdcos(0) -
Ffr
d
cos(180) newtons
c. (-Fpd
+
Ffr
d)
joules
correct
d.
Fpdcos(0) +
Ffr
d
cos(180) joules
e.
Fpdcos(180) +
Ffr
d cos(0)
kg m2/s2
correct
¢
Work, as
defined in physics
a.
Cannot have a sign
b. Is a
vector
c. Can
be positive or negative
correct
d. Can
only be positive or 0
e. Is a
scalar
correct
¢
Work
done by a varying force
a. Has
no meaning
b. Has
meaning only if there is no friction
c. Is
calculated using the same equation (6-1 in the text) as for a constant force
correct
d. Is a
vector
e. Can
be calculated using graphical methods or calculus
correct
¢
Which of
the following statements are true?
a.
Mechanical energy is the ability to do work
correct
b. The
translational kinetic energy of an object is given by (1/2)mv2
correct
c. The
net work done on an object is equal to the object’s change in kinetic
energy.
correct
d. The
statement above (c) is called the work-energy principle.
correct
e.
Gravitational potential energy is given by mgy
correct
¢
Which of
the following are true statements?
a. In
calculating work, the force of gravity acting on an object is a conservative
force.
correct
b. In
calculating work friction force acting on an object is a non conservative
force. correct
c.
Forces, for which work done doesn’t depend on the path, are called
conservative. correct
d.
Potential energy cannot be defined for a non conservative force.
correct
e. In
calculating work, the force of a spring acting on an object is a
conservative force.
correct
¢
Which of
the following statements are true?
a. Power
is defined as the rate at which work is done.
correct
b. In SI
units, power is measured in joules per second.
correct
c. In SI
units, power is measured in watts.
correct
d. Fs
= -kx, is known as Hooke’s law
correct
e. The
elastic potential energy of a spring is given by (1/2)kx2.
correct