Physics - October 2007

2 identical loudspeakers ar eplaced ona wall 2m apart. A listener stands 3m from the wall directly in front of one the speakers. A single oscillator is driving the speakers at a frequence of 300Hz.
a) what is the pahse different b/w the two waes when the reach the observer?

2007-10-18 13:33:18 · 1 answers · asked by Anonymous

Early one October you go to a pumpkin patch to select your Halloween pumpkin. You lift the 3.8 kg pumpkin to a height of 1.08 m, then carry it 50.1 m (on level ground) to the check-out stand.
(a) Calculate the work you do on the pumpkin as you lift it from the ground.

(b) How much work do you do on the pumpkin as you carry it from the field?

2007-10-18 13:30:21 · 1 answers · asked by Anonymous

so somehow i am suppose to prove that the 45 degree angle gives the biggest displacement. my teacher walked us through half of the steps and left us from there, help me figure out why the 45 degree angle gives the biggest displacement

it starts like this
x= the angle
Vyi [vetical initial velocity] V sin x
Vx- V cos x
Vyf - 0
T= ?
a[ acceleration due to gravity] =g
dx- horizontal displacement

to find the time in terms of v
Vf= Vi+at and from there we got t= [-Vsin x ]/ g

then to find the displacement
dx= V*t
dx= V cos x * [-Vsin x ]/ g
dx=[ -V^2] g * cos x * sin x

and we are suppose to take it from there , i understand that -[V^2] g part is a constant and the whole displacement basically depends on cos x * sin x and this is what is suppose to be the biggest. please show how u got that 45 degree angle gives biggest displacement. thanx

2007-10-18 13:24:08 · 1 answers · asked by Anonymous

What is Pythagoras,s thoery of the hypotenuse ,and why is it so simple and such a perfect,THRM.and such a perfect aid to all goematry and eguations

2007-10-18 13:09:43 · 3 answers · asked by oisintirnaog 2

Hannah rolls a 7.0 kg bowling ball down the alley. One pin is still standing, and Hannah hits it head-on with a velocity of 9.0 m/s. The 2.0 kg pin acquires a forward velocity of 14.0 m/s. What is the velocity of the bowling ball??

2007-10-18 13:07:59 · 1 answers · asked by Anonymous

A pitcher throws a baseball horizontally from the mound to home plate. The ball falls 0.918 m (3.01 ft) by the time it reaches home plate 18.3 m (60 ft) away. How fast was the pitcher's pitch?
(answer in m/s)

2007-10-18 13:06:35 · 2 answers · asked by Anonymous

Does it try to proved that there is nothing called time..
# Need real explanation ..plz....
# How does it relate to time..?

2007-10-18 13:04:00 · 1 answers · asked by world 1

A 0.06 kg pinecone falls 14.7 m to the ground, where it lands with a speed of 16 m/s.
(a) With what speed would the pinecone have landed if there had been no air resistance?

(b) Did air resistance do positive work, negative work, or zero work on the pinecone?
---Select--- positive negative zero

2007-10-18 12:57:02 · 1 answers · asked by Anonymous

2007-10-18 12:40:33 · 2 answers · asked by heeeysuzie 1

A physicist on planet Mongo is using a device equivalent to Atwood's machine to measure the Mongoian gravitational acceleration gm. He fixes one of the two 0.40kg masses at each end of the rope. While both are at rest, he places a 0.025kg gronch (a toadlike creature) on one of the masses. That body and its wart-covered passenger descend 0.50m before the gronch hops off. The body continues traveling downward another 0.8m in the next 3.0s. Compute gm.

please help me with the question.
I'm stuck for hours on this.

2007-10-18 12:36:13 · 2 answers · asked by Seongmo L 1

It travels 60 m during this time.
a) What is the car’s average acceleration?
b) What is its initial velocity?
.

2007-10-18 12:18:33 · 2 answers · asked by navya 1

A projectile is shot from the edge of a cliff h = 205 m above ground level with an initial speed of v0 = 115 m/s at an angle of 37.0° with the horizontal

(a) Determine the time taken by the projectile to hit point P at ground level.
s
(b) Determine the range X of the projectile as measured from the base of the cliff.
km
(c) At the instant just before the projectile hits the ground, find the horizontal and the vertical components of its velocity. (Take up and to the right as positive directions.) horizontal m/s
vertical m/s
(d) What is the the magnitude of the velocity?
m/s
(e) What is the angle made by the velocity vector with the horizontal?
° (below the horizontal)
(f) Find the maximum height above the cliff top reached by the projectile.
m

2007-10-18 12:12:47 · 2 answers · asked by kdcheerldr 1

A right triangle has an opposite =3 and an adjacent =5
1.Compute the hypotenuse
2.Compute sin theta
3.Compute theta

2007-10-18 12:05:05 · 3 answers · asked by lub1210 1

...even though i already no it i just want 2 c if u can figure it out................a cube has 2cm lenghth,4cm wide.0.5 cm height,and it weights 10 grams calculate the density!!!!!!!!

2007-10-18 12:00:35 · 8 answers · asked by Anon E. Mous 3

cable attached to its ends?

2007-10-18 11:57:10 · 1 answers · asked by Katherine L 1

in nuclear fission:
(a) certain atoms break into fragments when struck be neutrons
(b) a chain reaction does not occur
(c) energy is released mostly as light
(d) all of these

in nuclear fision:
(a) large atoms break apart into smaller atoms
(b) nuclei of atoms combine
(c) liquids are converted to solids
(d) elements combine to form compounds

2007-10-18 10:58:52 · 1 answers · asked by Jenn S 2

What Does the T mean

2007-10-18 10:49:50 · 2 answers · asked by jphoenix91 2

or Greece's ranking in football after the Euro qualifiers.

2007-10-18 10:49:00 · 4 answers · asked by Anonymous

A ray of light traveling in material A strikes the interface between materials A and B at an angle of incidence of 65.3 . The angle of refraction is 39 . Find the ratio nA/nB of the refractive indices of the two materials

2007-10-18 10:46:05 · 1 answers · asked by Anonymous

An object in equilibrium has three forces exerted on it. A 30 N force acts at 90° from the x-axis and a 44 N force acts at 60° from the x-axis. What are the magnitude and direction of the third force?

What is the third force(N)??
What is the degrees??° (counterclockwise from the +x direction)

2007-10-18 10:37:33 · 1 answers · asked by leekite69 1

is there a change when you catch the ball?

2007-10-18 10:35:06 · 3 answers · asked by heeeysuzie 1

A 2.00 kg block situated on a rough incline is connected to a spring of negligible mass having a spring constant of 100 N/m (Fig. P5.76). The block is released from rest when the spring is unstretched, and the pulley is frictionless. The block moves 21.2 cm down the incline before coming to rest. Find the coefficient of kinetic friction between the block and incline.

link: http://www.webassign.net/sf/p5_76.gif

help pleasee

2007-10-18 10:18:47 · 1 answers · asked by Anonymous

A child's pogo stick (Fig P5.75) stores energy in a spring (k = 2.40 104 N/m). At position A (x1 = -0.100 m), the spring compression is a maximum and the child is momentarily at rest. At position B (x = 0), the spring is relaxed and the child is moving upward. At position C, the child is again momentarily at rest at the top of the jump. Assume that the combined mass of child and pogo stick is 27.0 kg.

link: http://www.webassign.net/sercp/p5-75.gif

(a) Calculate the total energy of the system if both potential energies are zero at x = 0.

(b) Determine x2.

(c) Calculate the speed of the child at x = 0.

(d) Determine the value of x for which the kinetic energy of the system is a maximum.

(e) Obtain the child's maximum upward speed.

2007-10-18 10:17:04 · 1 answers · asked by Anonymous

just wondering

2007-10-18 10:17:01 · 2 answers · asked by Anonymous

I want to ask to questions but not use up 10 points.

Question #1
Work in physics is defined by one moving an object. My question is how is doing no work even possible, when just by standing at rest on (lets say) a floor we are bending it. The molecules in the floor are moving, so aren't we in fact doing work? Isn't bending something the same thing as doing work because there is movement on the molecular level? Please explain this if you can because I'm confused.

#2. can some energy be lost as it converts from one form to another(i.e. light to heat). The two forms are made of different properties, but would the mass of heat be equal to the mass that the light had? If yes, how can it if the properties are different. Basically how can energy go from one state to another without loosing part of itself as its properties change during conversion.. I mean you have to lose and gain something to change right? Is lost energy the same thing as destroyed.

I know there is error in my thinking

2007-10-18 10:12:30 · 3 answers · asked by Anonymous

using conservation of momentum and energy what is the velocity of the slower object after the collision and what is the velocity of the faster object after the collision?

2007-10-18 10:08:45 · 2 answers · asked by amy b 1

I was able to complete all of the other problems, but this one is much more difficult and I am completely lost..

A squirrel is wandering around a yard. It hops 2.2m at an angle of 74 degrees north of east. Then it scurries 3.1m at an angle of 85 degrees north of west. Finally, it runs 1.7m at an angle of 15 degrees south of west. What are the magnitude and direction for the squirrel's total displacement?

If anyone can help me I'd greatly appreciate it..Thanks!!

2007-10-18 09:10:56 · 4 answers · asked by Anonymous

i'm stuck on the last 3 questions. please help on any u know thanks.
1. A 20g ball of clay is thrown horizontally at 30m/s toward a 1.0kg block sitting at rest on a frictionless surface. The clay hits and sticks to the block.
a. What impulse does the clay exert on the block?
b. What impulse does the block exert on the clay?
c. Does J(block on clay) = -J(clay on block)?

2.A firecracker in a coconut blows the coconut into 3 pieces. Two peices of equal mass fly off south and west, perpendicular to each other , at 20m/s. The 3rd piece has twice the mass as the other two. What are the speed and direction of the 3rd piece.
3.A 10g bullet is fired into a 10kg wod block that is at rest on a wood table. The block, with the bullet embedded, slides 5.0cm across the table. What was the speed of the bullet?

2007-10-18 09:00:54 · 2 answers · asked by Anonymous

1. The lower block which is 2kg is pulled on by a rope with a tension force of 20N. the coefficient of kinetic friction between the lower block and the surface is 0.30. the coefficient of kinetic friction between the lower block and the upper block(1kg) is also 0.30. What is the acceleration of the 2.0kg block?


2. Find an expression for the acceleration of m1. Assume the table is frictionlesss.
m1 is a box on a surface being pulled by a pulley toward -->
m2 is a dangling box.

2007-10-18 08:52:42 · 1 answers · asked by Anonymous

can you show your solution please? I'm stuck on 2 of my homework questions.

41. In an old-fashioned amusement park ride, passengers stand inside a 5.0 m diameter hollow steel cylinder with their backs against the wall. The cylinder begins to rotate about a vertical axis. Then the floor on which the passengers are standing suddenly drops away! If all goes well, the passengers will "stick" to the wall and not slide. Clothing has a static coefficient of friction against steel in the range 0.6 to 1.0 and a kinetic coefficient in the range 0.4 to 0.7. A sign next to the entrance says "No children under 30kg allowed." What is the minimum angular velocity, in rpm, for which the ride is safe?

2. A 500g ball moves in a vertical circle on a 102cm long string. If the speed at the top is 4.0m/s, then the speed at the bottom will be 7.5m/s
a) What is the ball's weight?
b. What is the tension in the string when the ball at the top?
c. Tension in the string when the ball at bottom?

2007-10-18 08:48:44 · 1 answers · asked by Anonymous