Problem Sets
Problem Set 6 – Due October 31 @ 3pm
Take online quiz!
Conceptual question 16 from text.
Must be typed. Double spaced
<= 1 page.
Problem 19, Problem 30, Problem 40, Problem 49
Problem Set 5 – Due Oct 20 @ 4pm
Take your question 48 from Chapter 4 from last weeks assignment and
write a well formed (short!) report on exactly how you used Newton’s 3 laws
to solve the problem. I am not
interested in the math, just the application of the 3 laws.
One definition of a conservative force is: A force is conservative if
the net work done by the force in moving an object around a closed loop is
zero. Hypothesis: Gravity is a conservative force. Test your hypothesis by calculating the
net work (i.e. add up all the work done on each segment) done by gravity in the following closed
loop: Start at 0.0m, 0.0m. 5.0kg box moved right to (2.0m, 0.0m),
object is then moved upwards to (2.0m, 3.0m); object is moved left to (0m,3m); finally object is moved downwards to (0.0m, 0.0m).
Note: only calculate the work done by gravity! Finally make a conclusion regarding your
hypothesis.
Solve question 48 from Chapter 4 using WorkEnergy – if possible!
Do questions on WebCT (should be easier this
week!)
Problem Set 4 – Due Oct 13 @ 4pm
Complete questions on WebCT . You
can attempt 5 times! See me for login
problems.
A 900kg car is involved in an accident.
The car was originally going at 100km/h when the driver saw a moose
on the road. The driver (75kg)
slammed on the brakes, resulting in a deceleration of 0.9g. What is the net force on the car? How far will it take the driver to
stop? How much time to stop? If the driver hits the moose 2.0s after
applying the brakes, how fast is the car going when it hits the moose. Suppose the car is moving this fast when
it hits the moose. If we treat the
moose as a barrier causing the rest of the car to stop over a distance of
the crumple zone of the car (approximately 40cm), what force does the moose
exert on the car? What force is
exerted on the driver of the car?
Given serious injury will occur if the average acceleration on the
driver exceeds 20g, do you expect the driver to be injured when striking
the moose?
Do question 48 in Chapter 4.
______________________________________
Problem Set 3 – Due Sept 28 @ 2 pm
Complete questions on WebCT . You
can attempt 5 times! See me for
login problems.
Chinook salmon are able to move
upstream faster by jumping out of the water periodically; this behaviour
is called porpoising. Suppose a salmon swimming in still water
jumps out of the water with a speed of 6.26m/s at an angle of 45 degrees,
sails through the air a distance L before returning to the water, and then
swims a distance L underwater at a speed of 3.58m/s before beginning
another porpoising maneuver. Determine the average speed of the fish.
S student stands at the edge of
a cliff and throws a stone horizontally over the edge with a speed of
18.0m/s. The cliff is 50.0m above a
flat, horizontal beach. How long
after being released does the stone strike the beach below the cliff? With what speed and angle of impact does
the stone land?
____________
Problem Set 2 – Due Sept 22 @ 4pm
Chp2 Conceptual #12, Problems 22, 37, 46, 61 (Provide graphical solution
of question 61). Also hand in the inspectors report for your boss Hugo on
the Maria Andretti case First
Day on the Job.
22. The velocity vs time graph for an object
moving along a straight path is shown below. Find the average acceleration of the
object for time intervals: 05s, 5s15s, 020s. (b) find
the instantaneous acceleration at 2.0s, 10s and 18s.
37. A car starts from rest and travels for 5.0s with a uniform
acceleration of +1.5m/s^{2}.
The driver then applies the brakes, causing a uniform acceleration
of 2.0m/s^{2}. If the
brakes are applied for 3.0s, (a) how fast is the car going at the end of the
braking period, and (b) how far has the car gone?
46. Traumatic brain injury such as a concussion results when the head
undergoes a very large acceleration.
Generally, an acceleration less than 800m/s^{2} lasting for
any length of time will not cause injury, whereas
an acceleration greater than 1000m/s^{2} lasting for ate least 1ms
will cause injury. Suppose a small
child rolls off a bed that is 0.40 m above the floor. If the floor is hardwood, the
child’s head is brought to rest in approximately 2.0mm. If the floor is carpeted, this stopping
distance is increased to about 1.0cm.
Calculate the magnitude and duration of the deceleration in both
cases, to determine the risk of injury.
Assume that the child remains horizontal during the fall to the
floor. Note that a more complicated
fall could result in a head velocity greater or less than the speed you
calculate.
61. A young woman named Kathy Kool buys a sports car that can accelerate at the rate
of 4.90m/s^{2}. She decides
to test the car by drag racing with another speedster, Stan Speedy. Both start from rest, but experienced
Stan starts 1 second before and moves with a constant acceleration of
3.50m/s^{2}, find the (a) time it takes Kathy to overtake Stan, (b)
the distance she travels before she catches him, and (c) the speeds of both
cars at the instant she overtakes him.
Problem Set 1 – Due Sept 14 (1pm).
Chp 1
Conceptual #1: Estimate the order of magnitude of the length, in meters,
of each of the following: a) mouse b)pool cue c) basketball court d)elephant
e) city block
#2 What types of natural phenomena could serve as time standards?
Problem 32: Grass grows densely
everywhere on a quarteracre plot of land.
What is the order of magnitude of the number of blades of
grass? (1 acre = 43560 ft^{2})
Problem 39: For the right angle triangle a=6.00m, b=? c=9.00m below what
are a) the length of the unknown side
b) tangent of A and c) the sine of B.
Note side a is opposite
angle A and side c is the
hypotenuse and is opposite the right angle.
Provide 2 examples where you would use unit conversions in your everyday
life.
According to ICBC: 679 car crashes per day means that
there is a car crash every 3 minutes. Confirm this assertion.
