PHYS 102 Week 1 HW questions 100% correct

PHYS 102 Week 1 HW questions




Q1

A long-distance runner has an average speed of 3 m/s
during a race. How far does the runner travel in 39
minutes?
Step 1: Write down what you know in symbolic form:
Speed: v = 3 m/s
Time: t = 39 min = 39 min x 60 s/min = 2,340 s. In physics we use the MKS
system. Therefore, when solving problems your units need to be in
M(meter(m))K(kilogram(kg))S(second(s)) units.

Step 2: Write down what you don't know in symbolic form:
How far (distance): d =?

Step 3: Find an equation that contains what you know and what you don't
know:
d = vt

Step 4: Solve the equation for what you don't know
The equation is in the form we need.

Step 5: Plug in (substitute) what you know and you will find out what you
don't know:
d = vt = 3 m/s x 2,340 s = 7,020 m. Managing units: (m/s) x s = ms/s = m (s/s)
= m (since s/s = 1).

, PHYS 102 Week 1 HW questions




Q2
As a baseball is being thrown, it goes from 0.0 to 40.0 m/s
in 0.23 s.
(1) What is the acceleration of the baseball?

Step 1: Write down what you know in symbolic form:
v2 = 40.0 m/s and v1 = 0.0 m/s
t2 = 0.23 s and t1 = 0.0 s
Change in Speed: Δv = v2 - v1 = 40 m/s - 0 ms = 40 m/s
Change in Time: Δt = t2 - t1 = 0.23 s - 0.0 s = 0.23 s

Step 2: Write down what you don't know in symbolic form:
Acceleration: a = ?

Step 3: Find an equation that contains what you know and what you don't
know:
a = Δv/Δt

Step 4: Solve the equation for what you don't know:
The equation is in the form we need.

Step 5: Plug in (substitute) what you know and you will find out what you
don't know:
(a) a = Δv/Δt = (40 m/s)/(0.23 s) = 173.913 m/s^2 = 173.9 m/s^2 (rounded
to one decimal place).

(2) What is the acceleration in g's?

The acceleration in g's is the acceleration divided by the value of 1 g, which is
9.8 m/s2 or: (173.913 m/s2)/( 9.8 m/s2) = 17.74 g = 17.7 g (rounded to one
decimal place).