Wednesday

April 16, 2014

April 16, 2014

Total # Posts: 572

**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?

**Physics**

A small steel ball bearing with a mass of 24 g is on a short compressed spring. When aimed vertically and suddenly released, the spring sends the bearing to a height of 1.23 m. Calculate the horizontal distance the ball will travel if the same spring is aimed 27° from the ...

**Physics**

15.6 m/s. I understand now, thanks a bunch.

**Physics**

A stone thrown horizontally from a height of 7.8 m hits the ground at a distance of 12.0 m. Calculate the speed of the ball as it hits the ground. I was able to find the initial speed of the ball, which is 9.52 m/s. However, I'm unsure about whether I need to use this numb...

**Physics**

A snowball is launched horizontally from the top of a building at v = 15 m/s. If it lands d = 44.5 meters from the bottom, how high (in m) was the building? For this problem, do I need to solve for any other velocities? I'm a little stuck...I'm not quite sure how to so...

**Physics**

THANK YOU!

**Physics**

Salmon, swimming up the Fraser river to their spawning grounds, leap over all sorts of obstacles. The unofficial salmon-altitude record is an amazing 3.58 m jump. Assuming the fish took off at 45.0°, what was its speed on emerging from the water? Ignore friction. This prob...

**Physics**

Thanks, I got it now. :)

**Physics**

A rescue plane has to drop supplies to a group of castaways who are stranded on a deserted island. The plane is flying as 150 m/s at a level altitude of 1200 m. How far ahead of the landing zone should the plane release the supplies? I'm not even sure how to start this one...

**Physics**

At the entrance channel of a harbor, the tidal current has a velocity of 4.94 km/hr in a direction 23.2° south of east. Suppose a ship caught in this current has a speed of 15.6 km/hr relative to the water. If the helmsman keeps the bow of the ship aimed north, what will b...

**Physics**

At the entrance channel of a harbor, the tidal current has a velocity of 4.94 km/hr in a direction 23.2° south of east. Suppose a ship caught in this current has a speed of 15.6 km/hr relative to the water. If the helmsman keeps the bow of the ship aimed north, what will b...

**Physics**

*not sure

**Physics**

At the entrance channel of a harbor, the tidal current has a velocity of 4.94 km/hr in a direction 23.2° south of east. Suppose a ship caught in this current has a speed of 15.6 km/hr relative to the water. If the helmsman keeps the bow of the ship aimed north, what will b...

**Physics**

Great I got it, thanks. :)

**Physics**

I am given a velocity versus time graph for a runner. For it, I had to figure out the average velocity for the entire 16 s interval (for this, I got 2 m/s). Now they want me to find the displacement of the runner in the first 15.4 s. I know that it must be somewhere around 30 ...

**Physics**

A stone is thrown vertically upward. On its way up it passes point A with speed v, and point B, 12.6 m higher than A, with speed v/2. Calculate the maximum height reached by the stone above point B. I am still stuck on this problem, mainly because I can't seem to get v/2. ...

**Physics**

See, I use your method without rounding and now come up with 0.0852 s. So...now I'm a little stuck on which answer is the correct one.

**Physics**

A basketball player, standing near the basket to grab a rebound, jumps 73.6 cm vertically. How much time does the player spend in the bottom 15.4 cm of the jump? Ok...after this I swear I'm done! I just need someone to check my final answer, which is 0.0858 s.

**Physics**

A basketball player, standing near the basket to grab a rebound, jumps 73.6 cm vertically. How much time does the player spend in the bottom 15.4 cm of the jump? I need someone to check my work. I got about 3.797 as the inital velocity. I plugged this into "x = vt + 1/2at...

**Physics**

But don't I need time in order to find the initial velocity?

**Physics**

A basketball player, standing near the basket to grab a rebound, jumps 73.6 cm vertically. How much time does the player spend in the bottom 15.4 cm of the jump? I've been told that I need to use the height of the jump to solve for V. Then I need to use that V in the equat...

**Physics**

How can I solve for V if I don't yet have the time?

**Physics**

A basketball player, standing near the basket to grab a rebound, jumps 73.6 cm vertically. How much time does the player spend in the bottom 15.4 cm of the jump? I think I have this right, but I'd like someone to make sure. First I have to find the total time by plugging 7...

**Physics**

When finding the times, do I have to switch the cm to m?

**Physics**

Ok n/m, I got the answer. However, now it asks for the time in the bottom 15.4 cm. Do I have to use my time from the first problem to figure it out?

**Physics**

I found the time. Now I just have to double it, and that will be the time he spent in the top 15.4 cm?

**Physics**

To find the time, would I have to use the formula "x = vt + 1/2at^2?"

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