Physics - December 2007

2. Anne and Bill are watching a hot air balloon as it rises straight up from its launching pad in a flat field. At 1:30 the bottom of the balloon gondola is 47 feet above the landing pad and rising at a rate of 54 feet per minute. Anne is standing still on top of a 12 foot high ridge and is 38 feet west of the path of ascent. Bill is in the field 29 feet north of the pad and walking toward it at a rate of 78 feet per minute.
Anne’s eye level is at 5 feet. Let α be the angle of elevation as
Anne looks at the bottom of the gondola. Bill’s eye level is at 6 feet. Let β be the angle of
elevation as Bill looks at the bottom of the gondola.

2007-12-05 14:16:55 · 1 answers · asked by Anonymous

An ideal gas is in contact with a heat reservoir so that it remains at a constant temperature of 300 K. The gas is compressed from a volume of 33 L to a volume of 18 L. During the process the mechanical device pushing the piston to compress the gas is found to expend 7 kJ of energy. What is the magnitude of the heat flow between the heat reservoir and the gas in kJ?

2007-12-05 14:04:28 · 2 answers · asked by hehasnoidea2001 2

I have a quick question. We just finished boat races and I need to calcuate the bouyant force "exerted onto your boat by the water" as well as the "volume of water displaced by your boat."

We know that 1kg=1liter of water and 1 gallon=8.35lbs of water.

If you can please show me how (math-wise) I would appreciate it. I want to understand it too if I may ask, the answer is just a number but knowing how to calcuate it out is half the struggle. =)

2007-12-05 13:53:04 · 1 answers · asked by Greg J 2

2007-12-05 13:10:04 · 5 answers · asked by Danielle P 1

Which of the following does not result in an increase in the potential energy of the object involved?
A) air being pumped into a bicycle tire
B) water flowing down rapids
C) a weight being lifted off the ground
D) a roller coaster car moving uphill
E) a spring being stretched

2007-12-05 12:49:16 · 4 answers · asked by Anonymous

The A string of a violin is a little too tightly stretched. Four beats per second are heard when the string is together with a tuning fork that is oscillating accurately at concert A (440 Hz).

What is the period of the violin string oscillation?

Explain your work. Thanks!

2007-12-05 12:48:50 · 2 answers · asked by Anonymous

Organ pipe A, with both ends open, had a fundamental frequency of 300 Hz. The third harmonic of organ pipe B, with one end open, has the same frequency as the second harmonic of pipe A.

How long are (a) pipe A and (b) pipe B?

Explain your work. Thanks! :)

2007-12-05 12:48:10 · 2 answers · asked by Anonymous

A car travels for 1/2 hour at 40 km/h. How far does the car travel?

2007-12-05 12:47:59 · 2 answers · asked by i ♥ david a.=]] 2

only be 112 known elements. This is a homework question. I have read my book and I'm just not grasping what it's saying. Please don't bash me...I have really read it several times and I am just not seeing it and understanding it. Please explain...big test Friday and I need to do good on this test. Thank you.

2007-12-05 12:47:27 · 10 answers · asked by lizzye71 2

Calculate the work done by a o.47N force pushing a 0.026kg pencil 0.26m against a force of friction of 0.23N

2007-12-05 12:47:01 · 1 answers · asked by Pharaoh 1

The source of a sound wave has a power of 1.00 μW. If it is a point source, (a) what is the intensity 3.00 m away and (b) what is the sound level in decibels at that distance?

Explain your work. Thanks! :)

2007-12-05 12:42:58 · 2 answers · asked by Anonymous

IP A block with a mass of 3.1 kg is placed at rest on a surface inclined at an angle of 45° above the horizontal. The coefficient of static friction between the block and the surface is 0.50, and a force of magnitude F pushes upward on the block, parallel to the inclined surface. (a) The block will remain at rest only if F is greater than a minimum value Fmin, and less than a maximum value Fmax, Explain the reasons for this behavior. (b) Calculate Fmin (c) Calculate Fmax

2007-12-05 12:40:47 · 1 answers · asked by Anonymous

At the airport, you pull a 18-kg suitcase across the floor with a strap that is at an angle of 45° above the horizontal. Find (a) the normal force and (b) the tension in the strap, given that the suitcase moves with constant speed and that the coefficient of kinetic friction between the suitcase and the floor is 0.38.

2007-12-05 12:38:51 · 2 answers · asked by Anonymous

A projectile of mass 0.929 kg is shot from a cannon. The end of the cannon's barrel is at height 6.8 m. The initial velocity of the projectile is 9.5 m/s. The projectile rises to a max height of delta y above the end of the cannon's barrel and strikes the ground a horizontal distance delta x past the end of the cannon's barrel. Gravity is 9.8 m/s^2

The vertical component of the initial velocity at the end of the barrel where the projectile begins it's trajectory is 7.58 m/s and the max height delta y the projective achieves after leaving the end of the cannon's barrel is 2.93 m.
A) Determine the time it takes the projectile to reach its in max height in seconds.
B) How long does it take the projectile to hit the ground in seconds?
C) Find the magnitude of the velocity vector when the projectile hits the ground. Answer in m/s
D) Find the magnitude of the angle(with respect to the horizontal) the projectile makes when impacting the ground. Answer in degrees.
E) Find the range delta x

2007-12-05 12:36:22 · 1 answers · asked by Anonymous

After you pick up a spare, your bowling ball rolls without slipping back toward the ball rack with a linear speed of v = 3.22 m/s (Figure 10-24). To reach the rack, the ball rolls up a ramp that gives the ball a h = 0.50 m vertical rise. What is the speed of the ball when it reaches the top of the ramp?
m/s

2007-12-05 12:23:03 · 1 answers · asked by Amber G 2

A 115 kg astronaut and a 970 kg satellite are at rest relative to the space shuttle. The astronaut pushes on the satellite, giving it a speed of 0.18 m/s directly away from the shuttle. Seven-and-a-half seconds later the astronaut comes into contact with the shuttle. What was the initial distance from the shuttle to the astronaut?
m

2007-12-05 12:20:39 · 1 answers · asked by Amber G 2

Please help me. Thanks in advance.

1.) Katie pushes on a cow with a force of 200 N while John pulls on the cow with a force of 250 N. If the cow pushes back with a force of 325 N, what is the resultant force vector?

2.) Amanda is riding her flying cow towards north wth a velolcity of 280 m/s. If the wind blows from the west at 50 m/s, what is her resulant vector?

3.) If Alex pulls a cow with a force of 890. N with a rope that is 25 degrees to the horizontal, what are the X and Y components of the force exerted by Alex?

4.) A cow jumps off a diving board witha velocity of 9.5 m/s at a vertical angle of 22 degrees to the vertical. What are the X and Y components of the velocity?

5.) Bob pulls a cow in a wagon with a force of 55 N at an angle of 38 degrees to the horizontal. What are the X and Y components of the force?

2007-12-05 12:11:46 · 1 answers · asked by Serena 1

The A string of a violin is a little too tightly stretched. Four beats per second are heard when the string is together with a tuning fork that is oscillating accurately at concert A (440 Hz).

What is the period of the violin string oscillation?

Explain your work. Thanks!

2007-12-05 12:02:36 · 2 answers · asked by Anonymous

1) A reservoir behind a dam is 31 m deep. What is the gauge pressure at the base of the dam? The acceleration of grav-
ity is 9.8 m/s^2 and atmospheric pressure is
10100 Pa... Answer in units of kPa.

2) What is the gauge pressure 11 m from the top
of the dam? Answer in units of kPa.

2007-12-05 11:55:05 · 2 answers · asked by Anonymous

The source of a sound wave has a power of 1.00 μW. If it is a point source, (a) what is the intensity 3.00 m away and (b) what is the sound level in decibels at that distance?

Explain your work. Thanks! :)

2007-12-05 11:51:27 · 1 answers · asked by Anonymous

1. A mass m slides without friction down a slide and through a loop. If the mass remainis in the track (even at the top of the loop radius r) what hight must it be released from?

2. A 17 kg child descends a slide 3.5 m high and reaches the bottom with a speed of 2.5 m/s. How much thermal energy is released in the process?

2007-12-05 11:41:49 · 3 answers · asked by brubabe 5

Ok, first, thanks for taking the time for reading my question. Second I need help with these physics laws. I don't get the Faraday's law, the Coulomb's law, or the Ohm's law. Are just formuals are what? I need to explain them in a paper and I don't get them myself. Can you help me please! Thanks again!! = )

2007-12-05 11:32:27 · 4 answers · asked by ambey 3

Two roller skaters stand face to face then push each other away. One Skater has a mass of 90kg and the other has a mass of 60kg.

a. The velocity of the larger skater is 5.0m/s, with that what velocity is the smaller skater traveling at?

b. The smaller skater comes to a complete stop after 10s. How far from the original location is she and what is her deceleration?

thanks

2007-12-05 11:26:43 · 1 answers · asked by Anonymous

on a telescope is a photographic plate or a CCD more sensitive to light?

2007-12-05 11:26:17 · 1 answers · asked by xodanceox 2

A loaded penguin sled weighing 80 N rests on a plane inclined at 20° to the horizontal. Between the sled and the plane the coefficient of static friction is 0.24, and the coefficient of kinetic friction is 0.14.

(a) What is the minimum magnitude of the force F, parallel to the plane, that will prevent the sled from slipping down the plane?
wrong check mark N

(b) What is the minimum magnitude F that will start the sled moving up the plane?
N

(c) What value of F is required to move the block up the plane at constant velocity?
N

2007-12-05 11:25:39 · 2 answers · asked by Anonymous

If 281 g of water is contained in a 346 g
aluminum vessel at 6 C and an additional 85 g
of water at 81 C is poured into the container,
what is the final equilibrium temperature of
the mixture? Assume the specific heat of aluminum is 900 J/kg C. The specific heat of water is 4186 J/kg
C. Answer in units of C.

2007-12-05 11:25:23 · 1 answers · asked by yoyoyoyoyoyo 2

(a) Neglecting air friction, what initial speed would achieve this result?


(b) Using the speed determined in item (a), find the maximum height reached by the ball.

2007-12-05 11:18:16 · 1 answers · asked by Alyssa` L 1

1. From the point of view of an observer on the ground, the angle of elevation to a hot-air balloon 430 feet in the air is 20.4 degrees. How far is the observer from a point directly below the balloon?

2. A heavy piece of machinery is raised by sliding it 16.2 m along a plank oriented at 10.5° to the horizontal, as shown in Fig. 3-29 (substituting your numbers for those given in the figure).
How high above its original position is it raised
How far is it moved horizontally?

3. As shown in the accompanying diagram, a kite is flying at the end of a 25 meter string. If the string makes an angle of 65° with the ground, how high, to the nearest meter, is the kite?

4. If 0.00365 is written in scientific notation as 3.65 10n, find the value of n.

2007-12-05 11:00:01 · 1 answers · asked by Pieces Of Rainbowzz 4

2. why does a gymnast appear to be floating on air when she raises her arms above her head in a leap?
3. The rotational velocity of a merry-go-round in increased at a constant rate from 1.5/s to 3.5/s. What is the rotational acceleration of the merry-go-round?

2007-12-05 10:54:51 · 1 answers · asked by Anonymous

2007-12-05 10:50:58 · 1 answers · asked by Anonymous