Don’t waste time coloring in these letters… Get to work!
Due: ______________, ___ pts.
Name:____________________________________
_____________________________________________________________________________________________
Things to remember for success on this assignment:
i) Know your variables and their units
Δt = time in seconds
Δx =
Δy =
ii)
vi =
vf =
a=
Understand your equations. Make sure they are on your equation sheet.
v=
a=
Δy=
vf2 =
iii) Anything that is in the downward direction, you need to make _______________________.
iv)
If a number comes out negative in a calculation that tells you that the object is ___________________
or ____________________________.
v)
The acceleration due to gravity near the earth’s surface is _________.
vi) a) If you throw an object straight up, what is its speed at the top of its flight? ________
b) If you throw something straight up and it is in the air for a total of 8 seconds, how long did it take just
to go up? __________ sec.
vii) If you drop an object, what two variables do you know even though they are not stated in the problem?
__________________ and __________________
viii) You must use the format and show all of your work on all elligible problems except #1 for full credit.
list everything you know
Given:
the variable you are solving for
Unknown:
Equation: Write your equation first without numbers. Then plug the numbers in with the
correct units. Show how the units cancel. Put your final answers in a box with
the appropraite unit.
You will not be graded on significant figures on this assignment.
***IF YOU DON’T UNDERSTAND- see above, then ask a friend, then ask another group and then- ASK Mrs. G.***
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1.
Explain the difference between speed and acceleration including what units they are typically used.
2.
You are driving at a constant speed of 20m/s. What distance will you have covered at the end of the first 3
seconds?
Given:
Unknown:
Equation:
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3. a. In Rihanna’s song “Shut Up and Drive.” she says that she goes “0 to 60. in 3.5.” Calculate her acceleration.
(ans. 7.7 m/s2- Hint- Remember to convert the speed because they are singing about miles per hour!
You must show your work for the conversion.)
Given:
Unknown:
Equation:
b. How far would she have traveled in that time? (ans. 47 m)
For part b’s on problems, you start with the unknown because all of your givens should be listed in part a.
Unknown:
Equation:
4. a. You decide to drop your cat off the roof. Please do not try this at home. ☺ You figure he will free fall
through the air for 2.50 seconds. What will his final speed be? (Hint: It is falling downward, so your
speed will be negative. The acceleration due to gravity is also negative.) (ans. -24.5 m/s)
b. How far will the cat have fallen during that time? Solve this using two different equations. Make sure you
get the same answer for each. (ans. -30.6 m, It is negative because it is falling downward.)
For part b’s on problems, you start with the unknown because all of your givens should be listed in part a.
Unknown:
Equation 1:
Equation 2:
____________________________________________________________________________________________
****STOP! You must check your format off with Mrs. G. before moving on … her initials_______****
DO NOT COMPLAIN ABOUT THIS. This will help you to earn partial credit on tests. The format also
will help you to keep variables and equations straight in the future when we have 40-50 equations!
____________________________________________________________________________________________
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5. You throw a tennis ball vertically upward and it returns to your hand at the same height 6.0 seconds later.
a. For how many seconds did the ball fall after reaching its high point? __________ (Think about it. Your
guess is probably right!)
b.
How high did the ball go? (ans. -44 m because it would fall down through that distance)
6. You are driving at 55.1 miles per hour, and suddenly you see a deer in front of you. You apply the brakes at a
constant rate and bring your car to rest a in 21.4 seconds.
a. What is the acceleration? (A negative acceleration is the same as a deceleration.) (ans. -1.15 m/s2)
(Don’t forget to convert the speed. You need to show all of your work.)
b.
How far did you travel during that acceleration? (ans. 259 m)
7. A bullet leaves the muzzle of the gun at a speed of 410 m/s. The length of the gun barrel is 0.50 m. (that’s Δx)
Assuming the bullet was uniformly accelerated, how long was the bullet in the gun after it was fired?
(ans. 0.0024 sec. Hint: The answer is not 0.0012 sec. because it is not moving at a constant speed! This
is a 2-step problem. You need to solve for the acceleration first and then use that to get the time.)
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8. During a 30-second interval, the speed of a rocket rose steadily from 100 m/s to 500 m/s. How far did the
rocket go during this time? (ans. approximately 9,000 m)
9. An electron was uniformly accelerated from rest to a speed of 2.0 x 107 m/s in a particle accelerator.
a. If the electron traveled 0.10 m while being accelerated, what was its acceleration? (ans. 2.0 x 1015 m/s2)
b. How long did it take to attain its final speed? Solve this part using two different equations. Make sure you
get the same answer for each. (ans. 1.0 x 10-8 sec.)
10. A bullet is shot vertically upwards at an initial velocity of 908 miles per hour. Neglecting air resistance,
a. How long does it take before the bullet stops rising? (ans. 41.4 sec., Remember-convert your speed to m/.s)
b. how high does the bullet go during this time? (ans. approximately 8,400m or -8,400 m depending on how
you look at the problem, It is either going up through that distance or falling down that distance-either
answer is correct.)
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