[BMWPower06]

Ok since i got such great help from my last thread here is another

Problem 1:
Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. Consider the balls while they are both in flight. You may ignore air resistance. Which statements are true about this situation?
True False- Both are in free fall
True False- As time progresses, the difference between their accelerations increases
True False- As time progresses, the distance between them stays constant
True False- As time progresses, the difference between their velocities decreases
True False- Ball B will hit the ground after ball A



Problem 2:
You bring a large cannon along with you on a voyage to a distant planet. You set the cannon on a high cliff and you fire a cannonball horizontally off the cliff into an ocean. The cannonball follows projectile motion until it splashes into the water. Which of the following factors will determine the time that the cannonball is in flight? You should ignore atmospheric ("air") resistance.
yes no- height of cliff
yes no- mass of cannonball
yes no- planet's acceleration due to gravity
yes no- initial velocity of cannonball
yes no- radius of cannonball



Problem 3:
Three forces in the x-y plane act on a 4.50 kg mass: 15.10 N directed at 51o, 9.00 N directed at 142o, and 5.60 N directed at 219o. All angles are measured from the positive x-axis, with positive angles in the Counter-Clockwise direction. Calculate the magnitude of the acceleration.
I got the answer for this: 3.086 m/s^2

Calculate the direction of the resultant force using the same sign convention as above (in degrees).
But how do i do this?

Thanks Guys

[Josh49]

This stuff is easy.. If no one helps you out by tomorrow when I get to work, I'll help you out then..

[BMWPower06]

Originally Posted by Josh49

This stuff is easy.. If no one helps you out by tomorrow when I get to work, I'll help you out then..

got the first 2. Still need number 3 and this:

A fire helicopter carries a 561 kg bucket of water at the end of a 24.9 m long cable. Flying back from a fire at a constant speed of 43.6 m/s, the cable makes an angle of 48.4° with respect to the vertical. Determine the force of air resistance on the bucket.



and this:

A 2016-kg elevator moves with an upward acceleration of 1.86 m/s2. What is the tension in the cable that supports the elevator?

[ward]

problem 3 is just a trigonometery, vector adding type question

[BMWPower06]

Originally Posted by ward

problem 3 is just a trigonometery, vector adding type question

yea i just dunno how to find the angle.

[ward]

Originally Posted by BMWPower06

yea i just dunno how to find the angle.

use trig to break each vector into X and Y componants
then you can add them easily

you know the length of the hypotenuse of the triangle and one of the angles so you can find the length of the other 2 sides (which are the x,y componants)


what grade or level is this phyiscs BTW?

[ward]

Originally Posted by BMWPower06

and this:

A 2016-kg elevator moves with an upward acceleration of 1.86 m/s2. What is the tension in the cable that supports the elevator?

f=m*a

f=2016*1.86

[BMWPower06]

Originally Posted by ward

f=m*a

f=2016*1.86

i tried that, it said it was wrong...

[BMWPower06]

Originally Posted by ward

use trig to break each vector into X and Y componants
then you can add them easily

you know the length of the hypotenuse of the triangle and one of the angles so you can find the length of the other 2 sides (which are the x,y componants)


what grade or level is this phyiscs BTW?

yea i got the x,y components and i got the first part. I dont know how to do the second part of the question, which is asking for the degree of the angle.

This is level one college physics

[ward]

Originally Posted by BMWPower06

i tried that, it said it was wrong...

hmm do they give you any other info?

not sure what the difference is between force and tension? is tension like the force per area of the cable?

alot ot times they F with the units on problems to make it harder too, maybe that's part of it?

[NaTuReB0Y]

my brother is a chemistry/physics teacher....i'm sure he knows.

but me......i got a C+ in physics.....

[ward]

Originally Posted by BMWPower06

yea i got the x,y components and i got the first part. I dont know how to do the second part of the question, which is asking for the degree of the angle.

This is level one college physics

for the degree of the angle, you just have to do the first part backwards,
you have the X and Y componants, (2 sides of the triangle) use trig to find the angle

it's another f=ma question

[BMWPower06]

Originally Posted by ward

for the degree of the angle, you just have to do the first part backwards,
you have the X and Y componants, (2 sides of the triangle) use trig to find the angle

it's another f=ma question

which angle is it tho? This is what ive drawn, and ive already gotten the X,Y components.

[John]

#3

i got -.4315 for accel in x direction
3.05592 for y direction

magnitude is like you got 3.086
angle i got is 98.038

give that a shot

[BMWPower06]

Originally Posted by ward

hmm do they give you any other info?

not sure what the difference is between force and tension? is tension like the force per area of the cable?

alot ot times they F with the units on problems to make it harder too, maybe that's part of it?

i got it, it was F=MA then F + MG

but still stuck on the other one

[BMWPower06]

Originally Posted by John

i got .4315 for accel, try that

for which problem? and how?

[John]

sorry, look at my edited post above

[BMWPower06]

Originally Posted by John

#3

i got -.4315 for accel in x direction
3.05592 for y direction

magnitude is like you got 3.086
angle i got is 98.038

give that a shot

God i LOVE this forum. you are right, so howd u get the angle?

[ward]

Originally Posted by BMWPower06

which angle is it tho? This is what ive drawn, and ive already gotten the X,Y components.

angles are measured from positive X, so 0 degrees is straight right, 90 degrees is straight up, 180 is left, 270 is down

I'm not sure from your pic which vector is the result, but hopefully this helps

[John]

Originally Posted by BMWPower06

God i LOVE this forum. you are right, so howd u get the angle?

meh luck

do you have aim, i can better explain it to you on there,
but if you want i can explain in here, let me know

[Driv3r]

So this is level one college physics?? I should be set....not to far from what i learned in physics class actually i learned much of this...this is good news..what college do you attend BTW??

[BMWPower06]

Originally Posted by Driv3r

So this is level one college physics?? I should be set....not to far from what i learned in physics class actually i learned much of this...this is good news..what college do you attend BTW??

Yea this is about the first week of level one college physics. I go to George Washington University in DC. Where are you going?