**First Examination
**

Physics 103

23 September 1980
#1. To change **60 km/hr** to **ft/sec**, the appropriate conversion
is

**Answer:**

#2. A vector **R**, as
shown in the sketch, has a magnitude of **10 m** and makes an angle of **30**^{o}
with the **+x-axis**. The vector **R**
is most closely equal to

**Answer:**

#3. We are given the vectors

**
A = 3 i
+ 4 j
**

B = i
- 2 j
+ 2 k

Let ** q **be the angle between
**A
** and **B**. Which of these statements is true?

**Answer:**

#4. A car travels **6 km** **EAST** for **4 minutes**, then **8
km** **NORTH **for **6 minutes**. The **average velocity** (**in
km/hr**) is most nearly equal to

**Answer:**

#5. The ** displacement vs time** curve for an object is given
below. The corresponding ** velocity vs time** curve would look like:

**Answer:**

#6. A rocket blasts off vertically from rest. A graph of its **
vertical velocity (m/sec)** versus ** time (sec)** is shown. The ** average
acceleration** of the rocket during the ** first 5 seconds** of flight is most nearly
equal to

**Answer:**

#7. A truck starts from rest and moves with **constant acceleration**.
At time **t**_{1 }it has a speed of **10 m/sec**, and at a
later time **t**_{2} it has a speed of **15 m/sec**. During
the time interval (**t**_{1}, **t**_{2}) it has
moved **100 m**. **Note**: This is one-dimensional motion. The
time interval between **t**_{1 }and_{ }t_{2}
is

**Answer:**

#8. In Problem **#7**, the **acceleration **of the truck is

**Answer:**

#9. An "el" train **accelerates uniformly** from rest to **60
mi/hr** in **15 seconds**. It maintains that **constant velocity**
for **45 seconds**, and then decelerates to rest in **10 seconds**. The**
total distance traveled** is most nearly equal to

**Answer:**

#10. An object is dropped from rest from a bridge **36 feet** above a
lake. It falls with a **uniform acceleration** of **32 ft/sec**^{2}
until it hits the water; then it sinks with its **constant
"splashdown" velocity**. **Three seconds** after it was
dropped, the object reaches the bottom of the lake. What is the **depth**
of the lake?

**Answer:**

#11. A ball is thrown vertically straight up (**in the +y direction**). At
the position of its ** maximum altitude** it is true that

**Answer:**

#12. A football player kicks a ball **200 feet** (ground to ground) from its initial position. If
the ** angle** of the initial velocity with respect to the ground is **30**^{0}, the
** magnitude
of the initial velocity** is most nearly equal to

**Answer**

#13. A bullet is fired with an initial velocity **v**_{0} at a
target **x feet** away. the expression giving the vertical
displacement **y** from the initial line of sight (**x-axis**) is: **Hint**:
do **not** neglect gravity.

**Answer**

14. An airplane traveling at **150 m/sec** at an angle of **30**^{o }__below__
the horizontal, drops a package from a height of **1000 m**. The **horizontal
displacement** of the package when it hits the ground, __ relative to the drop
point__, is approximately

**Answer:**

#15. A car travels around a ** circular track** at a fixed speed of **50 ft/sec**
in a time of **20 seconds**. The ** radial acceleration** experienced by the
car is

**Answer:**