Friday
July 25, 2014

Posts by lindsay


Total # Posts: 598

Physics
Great I got it, thanks for all your help.

Physics
My last problem for the day: A) The centers of two 11.00 kg spheres are separated by 0.09 m. What is their gravitational attraction? I got 9.96 x 10^-7 N. B) What is the ratio of this attraction to the weight of one of the spheres (at the surface of the Earth)? I'm sure th...

Physics
Oh ok I see. Well, my online homework site would only accept it as postive, but it has been known to make errors before.

Physics
I tried both of the ways and got the same answer. However, the answer I got using bobpursley's equation got me -5.11E-8, when it was really positive. Was there an error in that equation, or did I just mess up with the math somewhere along the way?

Physics
Three very small spheres are located along a straight line in space far away from everything else. The first one (with a mass of 2.43 kg) is at a point between the other two, 10.60 cm to the right of the second one (with a mass of 5.17 kg), and 20.70 cm to the left of the thir...

Physics
The Wall of Death in an amusement park is comprised of a vertical cylinder that can spin around the vertical axis. Riders stand against the wall of the spinning cylinder and the floor falls away leaving the riders held up by friction. The radius of the cylinder is 3.8 m and th...

Physics
This is the info for the problem: A block of mass M1 = 160.0 kg sits on an inclined plane and is connected to a bucket with a massless string over a massless and frictionless pulley. The coefficient of static friction between the block and the plane is ms = 0.52, and the angle...

Physics
Ahhh ok that was what was wrong. Thanks a ton. :)

Physics
A youngster shoots a bottle cap up a 15.0° inclined board at 1.92 m/s. The cap slides in a straight line, slowing to 0.95 m/s after traveling some distance. If the coefficient of kinetic friction is 0.35, find that distance. I still get 0.315 m as the answer, but it's ...

Physics
Ok I got it, thanks. The last part is this: Suppose the coefficient of kinetic friction between the block and the inclined plane is muk = 0.36. If M2 = 217.1 kg, what is the magnitude of the acceleration of M1? Which equation am I using for this?

Physics
That's right. Now it asks for the minimum value of M2 for which the system will remain at rest. Do I still use mgSinTheta-mg*mu*CosTheta?

Physics
A block of mass M1 = 160.0 kg sits on an inclined plane and is connected to a bucket with a massless string over a massless and frictionless pulley. The coefficient of static friction between the block and the plane is ms = 0.52, and the angle between the plane and the horizon...

math
49% is 0.49 as a decimal, and 80% is 0.80 as a decimal. 0.49 x 0.80 = 0.392, or 39.2%

Physics
Using 21.6 as the angle for both cos and sin, I come up with 33.91, which is the incorrect answer. Am I still doing something wrong?

Physics
Why is it sin and cos of 23.5? I thought the angle was 21.6...

Physics
Do you come up with an answer of 33.91? Because that's what I get.

Physics
Ok I understand that part. Now it asks for the minimum magnitude of F that will start the block moving up the plane, and the magnitude of F that is required to move the block up the plane at constant velocity. Is it a similar process for both?

Physics
A block weighing 70.7 N rests on a plane inclined at 21.6° to the horizontal. The coefficient of the static and kinetic frictions are 0.23 and 0.12 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?...

Physics
I've entered this into the computer, but it says it's not right. Hmmmm...

Physics
I keep getting 0.315 m, but that's not right. What am I doing wrong?

Physics
A youngster shoots a bottle cap up a 15.0° inclined board at 1.92 m/s. The cap slides in a straight line, slowing to 0.95 m/s after traveling some distance. If the coefficient of kinetic friction is 0.35, find that distance. So I get that (1/2)MV^2 = MgX*sin 15 + Mg*muk*co...

Physics
A youngster shoots a bottle cap up a 15.0° inclined board at 1.92 m/s. The cap slides in a straight line, slowing to 0.95 m/s after traveling some distance. If the coefficient of kinetic friction is 0.35, find that distance. So I get that (1/2)MV^2 = MgX*sin 15 + Mg*muk*co...

Physics
What is V, in this case?

Physics
A youngster shoots a bottle cap up a 15.0° inclined board at 1.92 m/s. The cap slides in a straight line, slowing to 0.95 m/s after traveling some distance. If the coefficient of kinetic friction is 0.35, find that distance. I still don't quite understand this one. How...

Physics
Ahh ok, I didn't realize the masses cancel out. But of course you're right. That really was easy. :)

Physics
A hockey puck is sliding across a frozen pond with an initial speed of 6.5 m/s. It comes to rest after sliding a distance of 7.6 m. What is the coefficient of kinetic friction between the puck and the ice? I know this one is not that difficult. However, I can't seem to get...

Physics
Yeppp n/m it is correct. Thanks a lot. :)

Physics
I came up with 5079 N as my answer to a. Is that correct?

Physics
A 850.0-kg car travelling on a level road at 27.0 m/s (60.5 mi/hr) can stop, locking its wheels, in a distance of 61.0 m (200.1 ft). (a) Find the size of the horizontal force which the car applies on the road while stopping. (b) Find the stopping distance of that same car when...

Physics
A railroad flatcar is loaded with crates. The coefficient of static friction between the crates and the floor is 0.27. If the train is moving at 59.7 km/hr, in how short a distance can the train be stopped with a constant acceleration without causing the crates to slide? I'...

Physics
Ohh ok great I understand. Thanks a lot. :)

Physics
A 5.70 kg block located on a horizontal floor is pulled by a cord that exerts a force F = 10.4 N at an angle theta = 27.5° above the horizontal. The coefficient of kinetic friction between the block and the floor is 0.10. What is the speed of the block 6.1 s after it start...

Physics
So wait...do I use cos 15 to find the acceleration?

Physics
I come up with 0.233 m as my answer, but that's not right. What am I doing wrong?

Physics
A youngster shoots a bottle cap up a 15.0° inclined board at 1.92 m/s. The cap slides in a straight line, slowing to 0.95 m/s after traveling some distance. If the coefficient of kinetic friction is 0.35, find that distance. Can someone please show me the steps to solving ...

Physics
A youngster shoots a bottle cap up a 15.0° inclined board at 1.92 m/s. The cap slides in a straight line, slowing to 0.95 m/s after traveling some distance. If the coefficient of kinetic friction is 0.35, find that distance. I'm never sure which equation to use for the...

Physics
See, I thought that was right, too. But I plug that into my computer and it says it's not right. So I'm not sure what I'm doing wrong...

Physics
A block weighing 70.7 N rests on a plane inclined at 21.6° to the horizontal. The coefficient of the static and kinetic frictions are 0.23 and 0.12 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?...

Physics
A block weighing 70.7 N rests on a plane inclined at 21.6° to the horizontal. The coefficient of the static and kinetic frictions are 0.23 and 0.12 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?...

Physics
A block weighing 70.7 N rests on a plane inclined at 21.6° to the horizontal. The coefficient of the static and kinetic frictions are 0.23 and 0.12 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?...

Physics
A railroad flatcar is loaded with crates. The coefficient of static friction between the crates and the floor is 0.27. If the train is moving at 59.7 km/hr, in how short a distance can the train be stopped with a constant acceleration without causing the crates to slide? Ok so...

Physics
A railroad flatcar is loaded with crates. The coefficient of static friction between the crates and the floor is 0.27. If the train is moving at 59.7 km/hr, in how short a distance can the train be stopped with a constant acceleration without causing the crates to slide? Ok so...

Physics
A railroad flatcar is loaded with crates. The coefficient of static friction between the crates and the floor is 0.27. If the train is moving at 59.7 km/hr, in how short a distance can the train be stopped with a constant acceleration without causing the crates to slide? Ok so...

Physics
How do I find the mass?

Physics
A railroad flatcar is loaded with crates. The coefficient of static friction between the crates and the floor is 0.27. If the train is moving at 59.7 km/hr, in how short a distance can the train be stopped with a constant acceleration without causing the crates to slide? I hav...

Physics
For lift I got 1320, and for deltamass I got 304.76. Is this right? If so, do I have to add those to the netforce?

Physics
A research balloon of total mass 200 kg is descending vertically with a downward acceleration of 3.2 m/s^2. How much ballast must be thrown from the car to give the balloon an upward acceleration equal to 2.8 m/s^2, presuming that the upward lift of the balloon does not change...

Physics
N/m I finally got it. Thanks for all your help. :)

Physics
I come up with 0.96 m/s^2. Is this correct?

Physics
m is 68 kg?

Physics
A man stands on a scale in an elevator that is accelerating upward. The scale reads 731.6 N. When he picks up a 35.0 kg box, the scale reads 1108.2 N. The man weighs 68 kg. What is the acceleration of the elevator? What do I need to do in order to solve this?

Physics
A car that weighs 14900.0 N is initially moving at a speed of 57.0 km/hr when the brakes are applied and the car is brought to a stop in 4.8 s. Find the magnitude of the force that stops the car, assuming it is constant. I found a using Vf=vi+at...a = 11.88 m/s^2. Then I found...

Physics
Now it asks for the normal force exerted on the mass by the floor. Do I need to use the acceleration for that?

Physics
A block of mass 7.5 kg is pulled along a horizontal frictionless floor by a cord that exerts a force of 31.0 N at an angle 26.3° above the horizontal. What is the magnitude of the acceleration of the block? I have nooo clue what to do for this one. Can someone please show ...

Chemistry
C2H6 = 14 valence electrons There are 4 valence electrons in a C, so in 2 C there is 8. H has only one. 8 + (1 x 6) = 14 v.e.

Chemistry
17? I come up with 19, but you might want to double check that.

Physics repost
I come up with 13.6 N as my net force. Is this correct?

Physics repost
A 2 kg otter starts from rest at the top of a muddy incline 85 cm long ans slides down to the bottom in 0.5 s. What net external force acts on the otter along the incline? I know which equation I need to use. But how can I use the cm and s to get the acceleration?

Physics
A 2 kg otter starts from rest at the top of a muddy incline 85 cm long ans slides down to the bottom in 0.5 s. What net external force acts on the otter along the incline? I know which equation I need to use. But how can I use the cm and s to get the acceleration?

Chemistry
My worksheet gives me a list of chemical symbols, and each one makes a phrase. I have to figure out which each one says. The one I can't figure out has these symbols: Co, Mo, Tc, O, U, N, Ta, Re, Y Any guesses as to what the phrase could be?

Physics
A regulation volleyball court is L = 18.0 m long and a regulation volleyball net is d = 2.43 m high. A volleyball player strikes the ball a height h = 1.76 m directly above the back line, and the ball's initial velocity makes an angle q = 55° with respect to the ground...

Physics
A regulation volleyball court is L = 18.0 m long and a regulation volleyball net is d = 2.43 m high. A volleyball player strikes the ball a height h = 1.76 m directly above the back line, and the ball's initial velocity makes an angle q = 55° with respect to the ground...

Physics
Great, thanks. That helps a lot. But now I have to do a graph of velocity and the x/y directions. My velocity in the x-direction is a staight line, and the vel. of the y continually decreases. They ask me to explain why each line has the shape that it does in terms of slope an...

Physics
Ahh ok I see. There isn't anything I should add to them? I just want to make sure they are as complete as possible.

Physics
We're studying projectile motion in my Physics class right now, and last week we went outside and hit tennis balls with a bat. Now we must make graphs showing the position of the ball in both the x and y directions. I must also explain why each line has the shape that it d...

Physics
16.73 is the final?? Because again, it's not right. Hmm...

Physics
The soccer goal is 23.05 m in front of a soccer player. She kicks the ball giving it a speed of 17.97 m/s at an angle of 25.83 degrees from the horizontal. If the goalie is standing exactly in front of the net, find the speed of the ball just as it reaches the goalie. Bobpursl...

Physics - check my work
I finally got the right answer. And I was using the right equation for Vfy, just not using the right numbers.

Physics - check my work
Hmm yeah I figured Vfy was wrong. But I'm still a little confused on which I equation I DO need to use.

Physics - check my work
A cannon is fired from a cliff 190 m high downward at an angle of 38o with respect to the horizontal. If the muzzle velocity is 41 m/s, what is its speed (in m/s) when it hits the ground? Please check my work. I think it’s wrong, but I don’t know where I’m messi...

Math
You might have to correct me if I'm wrong, but I think... In order to calculate overtime pay, you must take your amount earned per hour and multiply it by 1.5. In your case, Eric's overtime rate would be $13.86/hour ($9.24 x 1.5 = $13.86). For double time, take the amo...

Algebra
There really is no formula for this. All you must do is add 8 to both sides. What you do to one side, you must do to the other. w-8 = 9 w-8(+8) = 9(+8) The eights cancel out on this side. Now you are simply left with w = 17. Make sense?

Physics repost
I keep getting the same answer as you. This is what I did to get my original answer: V^2 = sqrt[Vx^2 + Vy^2] where... Vx = 41 m/s * cos 38 Vy at impact can be calculated using Vy^2 = (41 sin 38)^2 + 2 g H I got 55.56 as my Vy. I have a feeling this is where I got messed up...

Physics repost
Would 59.5 be the final answer?? B/c that is not right, either...

Physics repost
A cannon is fired from a cliff 190 m high downward at an angle of 38o with respect to the horizontal. If the muzzle velocity is 41 m/s, what is its speed (in m/s) when it hits the ground? I keep getting 64.28 m/s as my answer, but it's not right. Could someone tell me exac...

Physics
I keep getting 64.28 m/s as my answer, but it's not right. What am I doing wrong?

Physics
V is 41 m/s, right?

Physics
A cannon is fired from a cliff 190 m high downward at an angle of 38o with respect to the horizontal. If the muzzle velocity is 41 m/s, what is its speed (in m/s) when it hits the ground? Which equations do I need for this?

Physics repost
A regulation volleyball court is L = 18.0 m long and a regulation volleyball net is d = 2.43 m high. A volleyball player strikes the ball a height h = 1.76 m directly above the back line, and the ball's initial velocity makes an angle q = 55° with respect to the ground...

Physics
Would my equation for the x-dir. be Vcos 55*T = 18, since it's the full length of the court? What would my height for the y-dir. be? Vsin 55*T - (g/2)T^2 = ???

Physics
Ok so I have the initial speed and the max height. Now it asks "At what initial speed must the ball be hit so that it lands directly on the opponent's back line?" Do I use a process similar to that of the first question?

Physics
Now it asks for the max. height. above the court reached by the ball. Do I use the equation Vf^2 = vi^2 + 2(g)(delta y) ?

Physics
A regulation volleyball court is L = 18.0 m long and a regulation volleyball net is d = 2.43 m high. A volleyball player strikes the ball a height h = 1.76 m directly above the back line, and the ball's initial velocity makes an angle q = 55° with respect to the ground...

Physics
This is probably really obvious, but I'm still not undertanding why you have to subtract one.

Physics
How did you come up with 39.96 Vh^2?

Physics
The launching speed of a certain projectile is 6.4 times the speed it has at its maximum height. Calculate the elevation angle at launching. I have noo idea how to start this one. Please help!

Physics
The soccer goal is 23.05 m in front of a soccer player. She kicks the ball giving it a speed of 17.97 m/s at an angle of 25.83 degrees from the horizontal. If the goalie is standing exactly in front of the net, find the speed of the ball just as it reaches the goalie. Do I nee...

Physics
Thanks!

Physics
A catapult on a cliff launches a large round rock towards a ship on the ocean below. The rock leaves the catapult from a height H = 35.0 m above sea level, directed at an angle theta = 46.7° above the horizontal, and with a speed v = 28.4 m/s. Assuming that air friction ca...

Physics
A stone is aimed at a cliff of height h with an initial speed of 62 m/s directed 45° above the horizontal, as shown in the Figure below. The stone strikes at A, 6.56 s after launching. What is the height of the cliff? Can someone please tell me which equation(s) I need to ...

Physics
A helicopter is flying in a straight line over a level field at a constant speed of 21.7 m/s and at a constant altitude of 11.5 m. A package is ejected horizontally from the helicopter with an initial speed of 21.6 m/s relative to the helicopter, and a direction opposite to th...

Physics
All right n/m, I finally got the answer. :)

Physics
All right. So this is what my equation looks like so far. I need to solve for Vx: 25Vx^2 = 313.786 + Vx^2 Correct?

Physics
And drwls...where is 0.2041 coming from?

Physics
But my number was correct, right? 17.714 m/s?

Physics
A ball is thrown horizontally from a height of 16.01 m and hits the ground with a speed that is 5.0 times its initial speed. What was the initial speed? Ok so I got a vertical final velocity of 17.714 m/s. Now I need to find the horizontal speed, correct? Which equation can I ...

Physics
Ok makes sense. The only part I'm a little confused about is finding the horizontal speed...which equation is that?

Physics
A ball is thrown horizontally from a height of 16.01 m and hits the ground with a speed that is 5.0 times its initial speed. What was the initial speed? This question really boggles my brain. I have no idea how to solve this, given only the height. Could someone please steer m...

Physics
Ahh ok I got it now. Thanks. :)

Physics
Once I then have the initial vel., how can I go about getting the horizintal distance? Don't I need time?

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