•1 SSM Earth is approximately a sphere of radius 6.37 × 106 m.
What are (a) its circumference in kilometers, (b) its surface area
in square kilometers, and (c) its volume in cubic kilometers?
2-The micrometer (1 μm) is often called the micron. (a) How
many microns make up 1.0 km? (b) What fraction of a centimeter
equals 1.0 μm? (c) How many microns are in 1.0 yd?
3. The fastest growing plant on record is a Hesperoyucca whipplei
that grew 3.7 m in 14 days. What was its growth rate in micrometers
per second?
4. Earth has a mass of 5.98 × 1024 kg. The average mass of the atoms
that make up Earth is 40 u. How many atoms are there in Earth?
5. Iron has a density of 7.87 g/cm3, and the mass of an iron atom
is 9.27 × 10−26 kg. If the atoms are spherical and tightly packed,
(a) what is the volume of an iron atom and (b) what is the distance
between the centers of adjacent atoms?
Part 2:
1. While driving a car at 90 km/h, how far do you move while
your eyes shut for 0.50 s during a hard sneeze?
2. An automobile travels on a straight road for
40 km at 30 km/h. It then continues in the same direction for
another 40 km at 60 km/h. (a) What is the average velocity of the
car during the full 80 km trip? (Assume that it moves in the positive
x direction.) (b) What is the average speed? (c) Graph x versus
t and indicate how the average velocity is found on the graph.
3. The position of an object moving along an x axis is given
by x = 3t − 4t2 + t3, where x is in meters and t in seconds. Find the
position of the object at the following values of t: (a) 1 s, (b) 2 s,
(c) 3 s, and (d) 4 s. (e) What is the object’s displacement
between t = 0
and t = 4 s? (f) What is its average velocity for the time interval
from t = 2 s to t = 4 s? (g) Graph x versus t for 0 ≤ t ≤ 4 s and indicate
how the answer
for (f) can be found on the graph.
4. You are to drive 300 km to an interview. The interview
is at 11:15 a.m. You plan to drive at 100 km/h, so you leave
at 8:00 a.m. to allow some extra time. You drive at that speed for
the first 100 km, but then construction work forces you to slow to
40 km/h for 40 km. What would be the least speed needed for the
rest of the trip to arrive in time for the interview?
5. At a certain time a particle had a speed of 18 m/s in
the positive x direction, and 2.4 s later its speed was 30 m/s in the
opposite direction. What is the average acceleration of the particle
during this 2.4 s interval?
6. SSM An electron with an
initial velocity v0 = 1.50 × 105 m/s
enters
a region of length
L = 1.00 cm where it is electrically
accelerated (Fig. 2-26). It emerges
with v = 5.70 × 106 m/s. What is its
acceleration, assumed constant?
7. An electric vehicle starts from rest and accelerates at a rate
of 2.0 m/s2 in a straight line until it reaches a speed of 20 m/s. The
vehicle then slows at a constant rate of 1.0 m/s2 until it stops. (a)
How much time elapses from start to stop? (b) How far does the
vehicle travel from start to stop?
8. A car traveling 56.0 km/h is 24.0 m from a barrier
when the driver slams on the brakes. The car hits the barrier 2.00 s
later. (a) What is the magnitude of the car’s constant acceleration
before impact? (b) How fast is the car traveling at impact?
9. Figure 2-29 depicts the motion
of a particle moving along an x axis with
a constant acceleration. The figure’s
vertical scaling is set by xs = 6.0 m. What
are the (a) magnitude and (b) direction
of the particle’s acceleration?
10. With what speed must a ball be thrown vertically
from ground level to rise to a maximum height of 50 m?
(b) How long will it be in the air? (c) Sketch graphs of y, v, and a
versus t for the ball. On the first two graphs, indicate the time at
which 50 m is reached.
11. At a construction site a pipe wrench struck the ground
with a speed of 24 m/s. (a) From what height was it inadvertently
dropped? (b) How long was it falling? (c) Sketch graphs of y, v, and
a versus t for the wrench.
12. As a runaway scientific balloon
ascends at 19.6 m/s, one of its
instrument packages breaks free of
a harness and free-falls. Figure 2-34
gives the vertical velocity of the
package versus time, from before it
breaks free to when it reaches the
ground. (a) What maximum height
above the break-free point does it
rise? (b) How high is the break-free
point above the ground?