Kinematics Physics help!
An object thrown up from a cliff at 10m/s reaches a velocity of 20m/s down as it lands. If the acceleration due to gravity is 9.8m/s^2, what is the object's displacement? How long did it take for the object to land form the time it was thrown up.
Please tell me the formula you used and why you used it.
February 28, 2011
11 Comments • Newest first
He's in either 10th or 11th. Cause you usually start physics in sophomore year or junior year. But most people do Chem in 10th grade before physics.
Anyways, to solve this, use the kinematics formulas. V^2=U^2+2as ; S=ut+1/2at^2, V=at+u. Solve for time first then use it to find the objects displacement.
You should draw a picture to depict the situation more visually. This helps you determine the forces involved to find what your trying to look for. Objects velocity, displacement, angle, etc. Notice that if you draw the picture, you can find the situation as a triangle. from here, you can find x and y components.
Probably in 10th
Final velocity, for displacement, y= (Vf^2-Vi^2)/2a. So y = ((20m/s)^2)- (10m/s)^2))/-2(9.8m/s^2)
For Time, you will need to use the quadratic formula. Just take the positive answer
[quote=Antonio06]My bad, you are right. Use this formula for displacement. Vf^2 = Vi^2-2*a*y. Look for y= (Vf^2-Vi^2)/2a.
And for time, just use y = Vi*t-1/2g*t^2[/quote]
Thanks a bunch. But, what's the variable f stand for again?
My bad, you are right. Use this formula for displacement. Vf^2 = Vi^2-2*a*y. Look for y= (Vf^2-Vi^2)/2a.
And for time, just use y = Vi*t-1/2g*t^2
[quote=Antonio06]I guess for displacement is 5.102 m, and it takes 1.0204 seconds to land[/quote]
answer is -15 M for displacement
and 3.1 s for time.
I guess for displacement is 5.102 m, and it takes 1.0204 seconds to land
[quote=Thenubbies]Then why ask a question if you arnt willing to do it?[/quote]
Cause I have 10 other questions similar to this. Plus, I'm multi-tasking, studying for a precal test
edit: Well, this is the last and first time I'm going to be asking for help on Basil. I've been a member for 2years , I ask one question, and no one can help me. I feel rewarded answering to people's questions when they ask. Thanks Basil Community, you're amazing. Terrible.
[quote=Xyimous]Can you tell me the answers you got? I have the answer for the question, but I don't want to learn a procedure that doesn't work. Thanks[/quote]
Then why ask a question if you arnt willing to do it?
[quote=sykku]I used the equation for free fall acceleration.
vf^2 = vi^2 + 2*a*d
plug in the givens and find the d, or how high it rises.
next, use
d = vi*t + (1/2)*a*t^2[/quote]
Can you tell me the answers you got? I have the answer for the question, but I don't want to learn a procedure that doesn't work. Thanks
[quote=MemoriesOfMaple]Ugh. Are you in 8th grade by any chance?[/quote]
No. But can you do the question?