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January 31, 2015

January 31, 2015

**Recent Homework Questions About Physics**

Post a New Question | Current Questions

**Physics**

A dart gun is aimed horizontally at the center of a large target 150 m away. The initial velocity of the dart is 450 m/s. (Ignore air resistance) a) Where does the dart strike the target (relative to the center of the target)? b) To hit the center of the target the dart must ...
*Saturday, December 6, 2014 at 8:09pm*

**Physics**

Two noises produce sound levels of 70 and 80 dB when acting separately. Find the sound level in dB when the sources act together.
*Saturday, December 6, 2014 at 7:08pm*

**Physics Electric**

The electric potential in a region is given by V(x,y,z) = -10.0x^2 + 20.0xyz + 6.0y^3 a) Find the electric field that produces this potential? b) Find the amount of charge contained within a cubic region in space 20 cm on a side and centered at the point (10.0 cm, 10.0 cm, 10....
*Saturday, December 6, 2014 at 6:47pm*

**physics I**

A spherical reservoir that contains 4.55 105 kg of water when full. (h = 7.70 m.) The reservoir is vented to the atmosphere at the top. For a full reservoir, find the gauge pressure that the water has at the faucet in each house. Ignore the diameter of the delivery pipes. (The...
*Saturday, December 6, 2014 at 6:36pm*

**Physics**

bobpursley, is answering questions on this all you do?
*Saturday, December 6, 2014 at 4:19pm*

**Physics**

The force required to stretch a spring varies directly with the amount the spring is stretched. A force of 29 pounds is needed to stretch a spring 39 inches. How much force is required to stretch the spring 27 inches? Answer in units of lb
*Saturday, December 6, 2014 at 4:13pm*

**Physics**

Two forces are applied to a car in an effort to accelerate it, as shown below. The first force, F1 = 400 N, is applied at an angle α = 32° to the forward dashed line. The second force, F2 = 536 N, is applied at an angle β = 10° to the forward dashed line. (a...
*Saturday, December 6, 2014 at 4:06pm*

**PHYSICS : I NEED HELP PLEASE**

a 33 kg lawnmower is pulled by a 100N force on flat ground. The handle makes a 10 degree angle with the ground. The coefficient of friction between grass and lawnmower wheels is 0.10. Calculate normal force, force of friction and acceleration
*Saturday, December 6, 2014 at 3:18pm*

**Physics: need detailed answer**

a 33 kg lawnmower is pulled by a 100N force on flat ground. The handle makes a 10 degree angle with the ground. The coefficient of friction between grass and lawnmower wheels is 0.10. Calculate normal force, force of friction and acceleration
*Saturday, December 6, 2014 at 2:52pm*

**Physics**

Two artifacts in a museum display are hung from vertical walls by very light wires. Wire T1 is horizontal from the left wall and goes to a center weight of 177N and wire T2 is at a 53 degree angle with the right wall heading from right to left downwards towards the center ...
*Saturday, December 6, 2014 at 2:27pm*

**Physics**

A student uses a 2.00-m-long steel string with a diameter of 0.90 mm for a standing wave experiment. The tension on the string is tweaked so that the second harmonic of this string vibrates at 22.0Hz . (ρsteel=7.8⋅103 kg/m3) If you wanted to increase the first ...
*Saturday, December 6, 2014 at 12:46pm*

**physics**

what impulse is needed to slow a 45kg object from 15m/s to 12m/s?
*Saturday, December 6, 2014 at 12:23pm*

**physics**

steven throws a 3.5kg ball at a speed of 25m/s. what is the momentum of the ball? Please show work
*Saturday, December 6, 2014 at 12:09pm*

**physics**

Assume all temperatures to be exact, and neglect significant figures for small changes in dimension. A diver releases an air bubble of volume 4.0cm3cm^3 from a depth of 16mm below the surface of a lake, where the temperature is 8.0∘C. What is the volume of the bubble ...
*Saturday, December 6, 2014 at 10:59am*

**Physics**

A vertical cylindrical tank contains 1.80 mol of an ideal gas under a pressure of 1.00 atm at 20.0oC. The round part of the tank has a radius of 10.0 cm, and the gas is supporting a piston that can move up and down in the cylinder without friction. (a) What is the mass of this...
*Saturday, December 6, 2014 at 4:54am*

**Physics**

A cylinder 1.00 m tall with inside diameter 0.120 m is used to hold propane gas (molar mass 44.1 g/mol). It is initially filled with gas until the gauge pressure is 1.30 x 106 Pa and the temperature is 22.0oC. The temperature of the gas remains constant as it is partially ...
*Saturday, December 6, 2014 at 4:50am*

**physics**

What is the magnetic force by infinite wire on on a loop in magnetic field ?
*Saturday, December 6, 2014 at 1:42am*

**physics**

A ship maneuvers to within 2.47×103 m of an island’s 1.76 × 103 m high mountain peak and fires a projectile at an enemy ship 6.13 × 102 m on the other side of the peak, as illustrated. The ship shoots the projectile with an initial velocity of 2.54×...
*Saturday, December 6, 2014 at 1:27am*

**physics**

how many significant digits are in the following measurement 2.546m
*Friday, December 5, 2014 at 10:57pm*

**Physics Questions Help Please!**

1) The lowest tone to resonate in an open pipe of length L is 1600 Hz. What is the frequency of the lowest tone that will resonate in a closed pipe of length 2L? a) 100 Hz b) 1.60 Hz c) 200 Hz d) 0.800 kHz 2) Which of the following does not increase as a sound becomes louder? ...
*Friday, December 5, 2014 at 10:50pm*

**physics**

how many significant digits are in the following 2,546m
*Friday, December 5, 2014 at 10:48pm*

**Physics**

A computer hard drive rotates at 5400 revolutions per minute. Starting from rest, what torque will get the hard drive up to that speed in just 150 revolutions? The moment of inertia of the hard drive is 1.3×10^-2 kg·m^2. I know the answer is 2.2 N.m, but I'm not...
*Friday, December 5, 2014 at 10:26pm*

**physics**

You want to set up a standing wave on a string that has a length of 3.7 m. You find that the lowest frequency that will work is 46 Hz. What is the speed of a wave on this string?
*Friday, December 5, 2014 at 10:20pm*

**Physics**

A projectile is shot straight up from the earth's surface at a speed of 1.20 x 104 km/hr. How high does it go?
*Friday, December 5, 2014 at 8:15pm*

**Physics**

A horse draws a sled horizontally on snow at constant speed. The horse can produce a power of 1.095 hp. The coefficient of friction between the sled and the snow is 0.115, and the mass of the sled, including the load, is 187.6 kg. What is the speed with which the sled moves ...
*Friday, December 5, 2014 at 7:58pm*

**Physics**

A car of mass 1335.0 kg is moving at a speed of 60.4 mph when it misses a curve in the road and hits a bridge piling. If the car comes to rest in 0.214 s, how much average power (in watts) is expended in this interval?
*Friday, December 5, 2014 at 7:56pm*

**physics**

A 92 kg clock initially at rest on a horizontal floor requires a 656 N horizontal force to set it in motion. After the clock is in motion, a horizontal force of 560 N keeps it moving with a constant speed.
*Friday, December 5, 2014 at 5:23pm*

**physics**

A girl coasts down a hill on a sled, reaching the bottom with a speed of 8.6 m/s. The coefficient of friction between the sled's runners and the snow is 0.050, and the girl and sled together weigh 670 N. How far does the sled travel on the surface before coming to rest?
*Friday, December 5, 2014 at 4:54pm*

**Physics**

Someone please help me! I've been stuck on this problem for a while now and i can't figure it out! A disk with mass m = 5.2 kg and radius R = 0.44 m hangs from a rope attached to the ceiling. The disk spins on its axis at a distance r = 1.59 m from the rope and at a ...
*Friday, December 5, 2014 at 3:51pm*

**physics**

Assume that the Grand Bahama Island lies at the origin of the coordinate system shown in the diagram at below. Vector represents the hurricane's displacement at 44.5 km/h and vector represents its displacement after it shifts course three hours later and proceeds at a ...
*Friday, December 5, 2014 at 3:28pm*

**Physics circular motion **

A speed skater goes into a turn with a 31 meter radius. The skater has a speed of 14 m/s and experiences a centripetal force of 460 n. What is the mass of the speed skater
*Friday, December 5, 2014 at 11:46am*

**physics**

Three blocks A, B, and C are connected by two massless strings passing over smooth pulleys as shown below, with the 3.4-kg block on a smooth horizontal surface. Calculate the tension in the strings connecting A and B, and, B and C.
*Friday, December 5, 2014 at 11:26am*

**Physics**

The brakes of a bike (with a person) having a mass of 63 kg, reduces it's velocity from 8.5 m/s to 0 m/s in 3.0 seconds. What is the magnitude of braking force?
*Friday, December 5, 2014 at 11:08am*

**Physics**

A solid cylinder of mass 20 kg rotates about its axis with angular speed of 100 rad/sec. the radius of the cylinder is 0.25m. what is the kinetic energy of the cylinder?
*Friday, December 5, 2014 at 11:07am*

**Physics**

super mouse steals a large piece of cheese by rolling it across the floor with a force of 5.0 N. If the cheese has a mass of 50 kg with what acceleration does the cheese move? If super mouse's force remains constant, what will be the speed of the rolling cheese
*Friday, December 5, 2014 at 10:58am*

**Physics**

A 1600 kg car traveling at 13.7 m/s to the south collides with a 4600 kg truck that is initially at rest at a stoplight. The car and truck stick together and move together after the collision. What is the final velocity of the two-vehicle mass? Assume that North is positive. ...
*Friday, December 5, 2014 at 9:04am*

**Physics**

What is the force of attraction between an 8 kg bowling ball and a 13 kg cannon ball that are sitting 2 meters apart?
*Friday, December 5, 2014 at 8:13am*

**physics**

Sound is passing perpendicularly through an open window whose dimensions are 1.1 m x 0.75 m. The sound intensity level is 71 dB above the threshold of human hearing. How much sound energy comes through the window in one hour?
*Friday, December 5, 2014 at 7:05am*

**physics**

A man stands at the midpoint between two speakers that are broadcasting an amplified static hiss uniformly in all directions. The speakers are 28.0 m apart and the total power of the sound coming from each speaker is 0.602 W. Find the total sound intensity the man hears when (...
*Friday, December 5, 2014 at 7:04am*

**physics**

When an earthquake occurs, two types of sound waves are generated and travel through the earth. The primary, or P, wave has a speed of about 8.0 km/s and the secondary, or S, wave has a speed of about 4.5 km/s. A seismograph, located some distance away, records the arrival of ...
*Friday, December 5, 2014 at 7:04am*

**physics**

A jetskier is moving at 8.9 m/s in the direction in which the waves on a lake are moving. Each time he passes over a crest, he feels a bump. The bumping frequency is 1.15 Hz, and the crests are separated by 5.8 m. What is the wave speed?
*Friday, December 5, 2014 at 7:03am*

**physics**

The speed of a transverse wave on a string is 457 m/s, while the wavelength is 0.228 m. The amplitude of the wave is 2.05 mm. How much time is required for a particle of the string to move through a total distance of 1.34 km?
*Friday, December 5, 2014 at 6:57am*

**physics**

A roller coaster, loaded with passenger has a mass of 2000 kg; the radius of curvature of the track at the bottom point of the dip is 24 m. If the vehicle has a speed of 18m/s at this point, what force is exerted on the vehicle by the track? (g = 9.8 m/s2)
*Friday, December 5, 2014 at 1:02am*

**Physics**

An object is placed 5 cm in front of a concave lens of focal length 7 cm. Find the image location by drawing a ray tracing diagram to scale. Verify your answer using the lens equation. I am confused on what numbers would be negative in my formula of 1/f=1/v+1/u.
*Friday, December 5, 2014 at 12:13am*

**physics**

An object is placed 8 cm in front of a convex lens of focal length 6 cm. Find the image location by drawing a ray tracing diagram to scale. Verify your answer using the lens equation
*Thursday, December 4, 2014 at 11:49pm*

**physics**

Two lifeguards pull on ropes attached to a raft. If they pull in the same direction, the raft experiences a net external force of 376 N to the right. If they pull in opposite directions, the raft experiences a net external force of 162 N to the left. Draw a free body diagram ...
*Thursday, December 4, 2014 at 11:35pm*

**physics **

Due to a tune-up, the efficiency of an automobile engine increases by 4.00%. For an input heat of 1530 J, how much more work does the engine produce after the tune-up than before?
*Thursday, December 4, 2014 at 11:35pm*

**physics**

According to the manual of a certain car, a maximum torque of magnitude 76.0 N · m should be applied when tightening the lug nuts on the vehicle. If you use a wrench of length 0.276 m and you apply the force at the end of the wrench at an angle of 75.00° with ...
*Thursday, December 4, 2014 at 11:22pm*

**physics help PLZ!!**

What is the direction of the net external force on the crate (as an angle between −180◦ and 180◦ , measured from the positive x axis with counterclockwise positive)? Answer in units of ◦ Ive solved for the net external force in the x and y direction. Fx...
*Thursday, December 4, 2014 at 11:21pm*

**Physics**

Help!! I would greatly appreciate help with this question. Consider a pulse of laser light aimed at the Moon that bounces back to Earth. The distance between Earth and the Moon is 3.84 * 108 m. Show that the round-trip time for the light is 2.56s.
*Thursday, December 4, 2014 at 10:55pm*

**Physics**

You have a brass ring of inside diameter 10.00 cm that is at 20.0oC. You want to slip this ring over an aluminum rod that is at 20.0oC and has a diameter of 10.01 cm. a. To what temperature do you have to heat the ring to slip it over the rod? b. Once you have the ring over ...
*Thursday, December 4, 2014 at 10:53pm*

**ap physics**

a 37.4-kg traffic light is supported by two wires prove you answer applying newtons law
*Thursday, December 4, 2014 at 10:30pm*

**Physics**

A 31.5 N object is in free fall. What is the magnitude of the net force which acts on the object? Answer in units of N
*Thursday, December 4, 2014 at 8:42pm*

**physics**

A crate is pulled to the right with a force of 93.5 N, to the left with a force of 116.8 N, upward with a force of 658.1 N, and downward with a force of 248.6 N. What is the net external force in the x direction? Answer in units of N
*Thursday, December 4, 2014 at 8:33pm*

**Physics**

Batman (mass = 75.6 kg) jumps straight down from a bridge into a boat (mass = 631 kg) in which a criminal is fleeing. The velocity of the boat is initially +10.4 m/s. What is the velocity of the boat after Batman lands in it?
*Thursday, December 4, 2014 at 7:19pm*

**Physics**

A 2.86-g bullet, traveling at a speed of 452 m/s, strikes the wooden block of a ballistic pendulum, such as that in Figure 7.14. The block has a mass of 230 g. (a) Find the speed of the bullet/block combination immediately after the collision. (b) How high does the combination...
*Thursday, December 4, 2014 at 7:18pm*

**Physics**

A projectile, fired with unknown initial velocity, lands 18.4 s later on the side of a hill, 2740 m away horizontally and 469 m vertically above its starting point. (Ignore any effects due to air resistance.) (a) What is the vertical component of its initial velocity? 115.741 ...
*Thursday, December 4, 2014 at 7:12pm*

**physics**

A projectile is fired into the air from the top of a cliff of height h = 186 m above a valley. Its initial velocity is v0 = 64.8 m/s at an angle θ = 59° above the horizontal. Where does the projectile land? (Ignore any effects due to air resistance.)
*Thursday, December 4, 2014 at 6:40pm*

**Physics**

Question: A force of 25N pushes a curling rock from rest 1.0 m across a frictionless surface. Find the FINAL kinetic energy. attempts: Well i guess it would be changeinEk so i tried Wnet=changeinEk fnet x changeinD = 1/2mvf^2-1/2mvi^2 to fnet x changeinD +1/2mvi^2=1/2mvf^2 ...
*Thursday, December 4, 2014 at 5:56pm*

**physics**

A 90-kilogram physics student would weigh 2970 Newtons on the surface of planet X. What is the magnitude of the acceleration due to gravity on the surface of planet X?
*Thursday, December 4, 2014 at 4:47pm*

**Physics**

Question: A force of 25N pushes a curling rock from rest 1.0 m across a frictionless surface. Find the FINAL kinetic energy. attempts: Well i guess it would be changeinEk so i tried Wnet=changeinEk fnet x changeinD = 1/2mvf^2-1/2mvi^2 to fnet x changeinD +1/2mvi^2=1/2mvf^2 ...
*Thursday, December 4, 2014 at 4:31pm*

**physics**

A blue puck has a velocity of 3i –4j m/s. Its mass is 20 kg. What is its momentum?
*Thursday, December 4, 2014 at 2:45pm*

**physics**

A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.30 m × 2.22 m. On a certain day, the indoor temperature is 22°C and the outdoor temperature is 0°C. (Assume the thermal conductivity of the glass is 0.8 J/s · m · °C.) What is...
*Thursday, December 4, 2014 at 12:09pm*

**physics **

If the acceleration due to gravity on the earth is 9.8 m/s2, what is the acceleration due to gravity on Rams?
*Thursday, December 4, 2014 at 11:06am*

**physics**

A projectile is fired into the air from the top of a cliff of height h = 186 m above a valley. Its initial velocity is v0 = 64.8 m/s at an angle θ = 59° above the horizontal. Where does the projectile land? (Ignore any effects due to air resistance.)
*Thursday, December 4, 2014 at 9:49am*

**physics**

A river 400 m wide is flowing at a rate of 2.0 m/s. A boat is sailing at a velocity of 10 m/s with respect to the wate, in a direction perpendicular to the river. (a) Find the time taken by the boat to reach the opposite bank. (b) How far from the point directly opposite to ...
*Thursday, December 4, 2014 at 7:58am*

**physics**

A stone thrown horizontally from the top of a 18-m tower hits the ground at a point 18 m from the base of the tower. (Ignore any effects due to air resistance.) (a) Find the speed at which the stone was thrown. m/s (b) Find the speed of the stone just before it hits the ground...
*Thursday, December 4, 2014 at 7:35am*

**physics**

A 0.59 kg rubber ball has a speed of 1.50 m/s at point A and kinetic energy of 7.0 J at point B. (a) Determine the ball's kinetic energy at A Correct: Your answer is correct. J (b) Determine the ball's speed at B
*Wednesday, December 3, 2014 at 11:05pm*

**Physics**

A two head collision. One car weighs 45000 newtons and going at 15 meters per second. The other car is traveling at 25 meters per second and weighs 9000 newtons. How would I calculate velocity?
*Wednesday, December 3, 2014 at 10:59pm*

**Physics**

You throw a ball towards a wall at 15ms-1, and it bounces back at 10ms-1. What is the total change in velocity? (the answer is not 5m/s)
*Wednesday, December 3, 2014 at 10:32pm*

**physics**

A 58.0 kg pole vaulter running at 8.9 m/s vaults over the bar. If the vaulter's horizontal component of velocity over the bar is 1.0 m/s and air resistance is disregarded, how high was the jump?
*Wednesday, December 3, 2014 at 10:10pm*

**physics **

Dolphins of the open ocean are classified as Type II Odontocetes (toothed whales). These animals use ultrasonic "clicks" with a frequency of 54.9 kHz to navigate and find prey. Suppose a dolphin sends out a series of clicks that are reflected back from the bottom of ...
*Wednesday, December 3, 2014 at 8:59pm*

**physics **

A guitar string 61.8 cm long vibrates with a standing wave that has three antinodes. Which harmonic is this?
*Wednesday, December 3, 2014 at 8:58pm*

**College Physics**

Suppose a 10.0 kg fireworks shell is shot into the air with an initial velocity of 62.0 m/s at an angle of 80.0 degrees above the horizontal. At the highest point of its trajectory, a small explosive charge separates it into two pieces, neither of which ignite (two duds). One ...
*Wednesday, December 3, 2014 at 8:22pm*

**Physics**

A block of mass m is pulled across a level surface by a rope that makes an angle θ with the horizontal. The coefficient of friction is μ. (a) Determine the amount of force F required to slide the block at a constant velocity. (b) Determine the optimum angle at which ...
*Wednesday, December 3, 2014 at 7:49pm*

**physics**

A man pushes 100.0 N on the handle of a 40.0 kg lawnmower. The applied force is in the same direction as the handle, which is tilted 35.0° relative to horizontal. The coefficient of kinetic friction is 0.10. Find the amount of acceleration.
*Wednesday, December 3, 2014 at 7:46pm*

**physics**

An object of mass 2.0 kg starts from rest at the top of a frictionless curved ramp. At the bottom, it collides with and sticks to another 2.0-kg mass object. Together the objects then cross a small rough section where there is friction before leaving the edge of the table ...
*Wednesday, December 3, 2014 at 6:10pm*

**Physics**

The engine of an automobile develops 176 hp when rotating at a speed of 1340 rpm. What torque (in foot-pounds) does it deliver? I tried using some kinematic equations, but that didnt work at all. Then I tried doing something where I would take an integral, but then I dont know...
*Wednesday, December 3, 2014 at 5:40pm*

**physics**

a glider with a mass of 5 kg is moving to the right on a horizontal frictionless surface at 6 m/s when it collides with a 8 kg glider that is at rest. After the collision, the 8kg glider is moving to the right at 6 m/s. what are the speed and direction of the 5 kg glider ?
*Wednesday, December 3, 2014 at 5:00pm*

**physics**

A uniform ladder of mass 46 kg and 3.0 m in length is leaning against a frictionless vertical wall at an inclination of 60 degrees to the horizontal. A Window cleaner of mass 67.3 kg climbs up the ladder. What coefficient of friction between the ladder and ground is required ...
*Wednesday, December 3, 2014 at 3:50pm*

**physics**

Two identical guitar strings under 108 N of tension sound tones with frequencies of 528 Hz. The peg of one string slips slightly, and the tension in it drops to 91.0 N. How many beats per second are heard?
*Wednesday, December 3, 2014 at 3:00pm*

**Physics**

What's the difference between Inertia and Impulse? Because the definitions sound really similar.
*Wednesday, December 3, 2014 at 2:38pm*

**physics**

A 2.9-kg cart starts up an incline with a speed of 2.7 m/s and comes to rest 3.0 m up the incline. The total work done (the work of the net force) on the cart is:
*Wednesday, December 3, 2014 at 1:02pm*

**Physics**

Geologists place tiltmeters on the sides of volcanoes to measure the displacement of the surface as magma moves inside the volcano. Although most tiltmeters today are electronic, the traditional tiltmeter, used for decades, consisted of two or more water-filled metal cans ...
*Wednesday, December 3, 2014 at 1:01pm*

**PHYSICS **

A diving board length L = 5.20m that weighs 205N is supported by two pillars. One pillar is at the left end of the diving board, as shown below; the other is distance d = 1.70m away. Find the magnitude of the force exerted by the left pillar when a 90.0kg diver stands at the ...
*Wednesday, December 3, 2014 at 12:20pm*

**Physics**

A projectile, fired with unknown initial velocity, lands 18.4 s later on the side of a hill, 2740 m away horizontally and 469 m vertically above its starting point. (Ignore any effects due to air resistance.) (a) What is the vertical component of its initial velocity? m/s (b) ...
*Wednesday, December 3, 2014 at 12:15pm*

**physics**

if the radius from the discus to the axis of rotation is 1.4m, what is the linear velocity of the discus at the time of release?
*Wednesday, December 3, 2014 at 11:35am*

**Physics**

A plastic bag is filled with nitrogen at atmospheric pressure and 22.0 oC. Assume that the mass of the bag is negligible and take the temperature of the outside air to be 0 oC. With the help of this "balloon" we want to lift a 50.0 kg girl off her feet. How large a ...
*Wednesday, December 3, 2014 at 9:47am*

**Physics**

A projectile, fired with unknown initial velocity, lands 18.4 s later on the side of a hill, 2740 m away horizontally and 469 m vertically above its starting point. (Ignore any effects due to air resistance.) (a) What is the vertical component of its initial velocity? m/s (b) ...
*Wednesday, December 3, 2014 at 9:17am*

**Physics**

You are trying out for the position of place-kicker on a professional football team. With the ball teed 50.0 m from the goalposts with a crossbar 3.05 m off the ground, you kick the ball at 28 m/s and 31° above the horizontal. (a) Is the field goal attempt good? no yes (b...
*Wednesday, December 3, 2014 at 9:08am*

**physics**

A stretched string fixed at each end has a mass of 17 g and a length of 10.5 m. The tension in the string is 44.5 N. What is the vibration frequency for the third harmonic? Answer in Hz.
*Wednesday, December 3, 2014 at 9:07am*

**Physics**

The range of a cannonball fired horizontally from a cliff is equal to the height of the cliff. What is the direction of the velocity vector of the projectile as it strikes the ground? (Ignore any effects due to air resistance.) ° (below the horizontal)
*Wednesday, December 3, 2014 at 9:02am*

**Physics**

Elephants communicate via infrasound, at frequencies as low as 11 Hz that can travel up to 9 km. The intensity of these sounds can reach 106 dB, measured a distance of 4 m from the source. a) Determine the intensity level in W/m2 of the infrasound at 4 m from the source. b) ...
*Wednesday, December 3, 2014 at 8:57am*

**Physics**

A projectile is fired into the air from the top of a cliff of height h = 186 m above a valley. Its initial velocity is v0 = 64.8 m/s at an angle θ = 59° above the horizontal. Where does the projectile land? (Ignore any effects due to air resistance.)
*Wednesday, December 3, 2014 at 8:53am*

**physics**

An airplane traveling at v = 152 m/s emits a sound of frequency 1850 Hz. At what frequency does a stationary listener hear the sound as the plane approaches? Use 340 m/s for the speed of the sound and answer in Hz.
*Wednesday, December 3, 2014 at 8:51am*

**physics**

A 60 kg worker pulls buckets of sand from height of 10 m using a pulley fixed to a wooden beam.While he is pulling a 20 kg bucket filled with sand he slips and falls down holding the rope.Assuming that the worker did not collide with bucket,find the velocity of the worker at ...
*Wednesday, December 3, 2014 at 8:23am*

**Physics**

A stone thrown horizontally from the top of a 18-m tower hits the ground at a point 18 m from the base of the tower. (Ignore any effects due to air resistance.) (a) Find the speed at which the stone was thrown. m/s (b) Find the speed of the stone just before it hits the ground...
*Wednesday, December 3, 2014 at 8:20am*

**physics**

two ball A&B each have a chrge of 30micro C are apart 5cm ,what force does thecharge A exert on the charge B .At what distance will the force will be halved ?
*Wednesday, December 3, 2014 at 8:03am*

**physics**

A small crack occurs at the base of a 15.0 m high dam. The effective crack area through which water leaves is 1.30 *10-3 m2
*Wednesday, December 3, 2014 at 7:38am*

**physics**

A cannon barrel is elevated at an angle of 45°. It fires a ball with a speed of 250 m/s. (For the following questions, ignore air resistance.) (a) What height does the ball reach? m (b) How long is the ball in the air? s (c) What is the horizontal range of the cannon? km
*Wednesday, December 3, 2014 at 7:34am*

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