cq_1_131

#$&*

Phy 201

Your 'cq_1_13.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.

** **

Copy the problem below into a text editor or word processor.

• This form accepts only text so a text editor such as Notepad is fine.

• You might prefer for your own reasons to use a word processor (for example the formatting features might help you organize your answer and explanations), but note that formatting will be lost when you submit your work through the form.

• If you use a word processor avoid using special characters or symbols, which would require more of your time to create and will not be represented correctly by the form.

• As you will see within the first few assignments, there is an easily-learned keyboard-based shorthand that doesn't look quite as pretty as word-processor symbols, but which gets the job done much more efficiently.

You should enter your answers using the text editor or word processor. You will then copy-and-paste it into the box below, and submit.

________________________________________

A ball rolls off the end of an incline with a vertical velocity of 20 cm/s downward, and a horizontal velocity of 80 cm/s. The ball falls freely to the floor 120 cm below.

• For the interval between the end of the ramp and the floor, what are the ball's initial velocity, displacement and acceleration in the vertical direction?

V0 = 20 cm/s

‘ds_v_ = 120 cm

A = 980 cm/s^2

#$&*

• What therefore are its final velocity, displacement, change in velocity and average velocity in the vertical direction?

Vf = [sqrt] 20^2 + 2(980)(120)

Vf = + - 485.4 cm/s

V f = 485.4 cm/s

‘ds_v_ = 120 cm

Change in Velocity = 465.4 cm/s

vAve = 485.4 + 20 cm/s / 2 = 252.7 cm/s

#$&*

• What are the ball's acceleration and initial velocity in the horizontal direction, and what is the change in clock time, during this interval?

A = 0 cm/s^2

V0_x_ = 80 cm/s

‘dt = x = v0^2(t) + ½(a)(t^2)

‘dt = + - 0.5 s

‘dt = 0.5 s

#$&*

• What therefore are its displacement, final velocity, average velocity and change in velocity in the horizontal direction during this interval?

“dv = 80 cm/s as acceleration is constant at 0 cm/s^2

‘ds = 80 cm/s * 0.5 s = 40 cm

vAve = 80 cm/s

Vf = 80cm/s

#$&*

• After the instant of impact with the floor, can we expect that the ball will be uniformly accelerated?

Yes, because the horizontal motion is uniform motion.

That's only so while in free fall. The interaction of the ball with the floor is very likely to influence the horizontal acceleration during the time of contact between ball and floor. However the influence on horizontal motion might be small.

#$&*

• Why does this analysis stop at the instant of impact with the floor?

Because the floor is the impact of vertical motion, thus ending accelerated motion.

that ends the uniformly accelerated motion

#$&*

** **

1 hour

** **

10/5 4 pm

Good. Revise only if you have questions, but do check the link.

&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.

Then please compare your old and new solutions with the expanded discussion at the link

Solution

Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.

If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#