Scott Pratt
 PHY231, Spring 2006  Introduct
1
Midterm 1 (lecture students)
2 pt
From dimensional analysis considerations alone, mark
these formulas as either ’valid’ or ’invalid’.
Assume that
x
has dimensions of distance,
v
has dimensions of velocity,
t
has dimensions of time,
g
has dimensions of acceleration and
m
has dimensions of mass.
. v/x
= 7
g/v
1
.
A
valid
B
invalid
. m
(
x
+
vt
)
/
(1 +
gt/v
) =
mgt
2
/
2
2
.
A
valid
B
invalid
4 pt
Consider a projectile which strikes a target as shown
below. Ignore all forces except gravity. Point A refers to a
point just beyond the muzzle of the cannon, B refers to the
highest point in the trajectory and C refers to a point just
before landing on the cliff.
.
The vertical component of the velocity at
B
is
zero.
3
.
A
greater than
B
less than
C
equal to
.
The acceleration at
A
is
the acceleration at
C
.
4
.
A
greater than
B
less than
C
equal to
.
The horizontal component of the velocity at
A
is
than
the horizontal component of the velocity at
B
.
5
.
A
greater than
B
less than
C
equal to
.
The magnitude of the vertical component of the velocity
at
A
is
the magnitude of the vertical component of the
velocity at
C
6
.
A
greater than
B
less than
C
equal to
4 pt
A cannonball is fired directly upward with an initial
velocity of 90 m/s and lands on the cannon after a time T.
For the following statements, displacements and times are
measured relative to the point at which the cannonball left
the muzzle, and the upward direction is positive. Choose the
best answer.
.
For times t between 0 and T, the displacement of the can
nonball was
.
7
.
A
positive
B
negative
C
zero
D
positive, negative and zero at different times
.
At the highest point in the trajectory, the velocity of the
cannonball was
.
8
.
A
positive
B
negative
C
zero
D
positive, negative and zero at different times
.
For times t between 0 and T, the velocity of the cannonball
was
.
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 Spring '08
 smith
 Acceleration, Velocity, lecture students, Scott Pratt, Introduct Midterm

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