Friday

November 27, 2015
**Physics**

How far above the surface of the earth would you have to be before your weight is reduced by 13.52%?
*Thursday, November 12, 2015 by Rebecca*

**Physics**

Find the minimum initial speed of a projectile in order for it to reach a height of 2022 km above the surface of the earth.
*Thursday, November 12, 2015 by Rebecca*

**maths lit,physics,life science n tourism**

i don't know which career to choose can you help me ?I'm doing grade 11.
*Thursday, November 12, 2015 by anita *

**AP Physics**

A 5.86 kg block initially at rest is pulled to the right along a horizontal surface by a constant, horizontal force of 14.4 N. The coefficient of kinetic friction is 0.14. The acceleration of gravity is 9.8 m/s 2 . Find the speed of the block after it has moved 4.98 m. Answer ...
*Wednesday, November 11, 2015 by Robert*

**Physics**

A plane landing on a small tropical island has just 80 m of runway on which to stop. If its initial speed is 65 m/s, what is the maximum acceleration of the plane during landing, assuming it to be constant? Answer in units of m/s 2
*Wednesday, November 11, 2015 by Kyle*

**Physics**

What is its centripetal acceleration? Answer in units of m/s 2 .
*Wednesday, November 11, 2015 by Elisabeth*

**Physics**

An athlete swings a 2.01 kg ball horizontally on the end of a rope. The ball moves in a circle of radius 0.98 m at an angular speed of 0.44 rev/s. What is the tangential speed of the ball? Answer in units of m/s.
*Wednesday, November 11, 2015 by Elisabeth*

**Physics**

A person of mass 81.7 kg escapes from a burning building by jumping from a window situated 28.9 m above a catching net. The acceleration of gravity is 9.8 m/s^2 . If air resistance exerts a force of 123.1 N on him as he falls, determine his speed just before he hits the net. ...
*Wednesday, November 11, 2015 by Anonymous*

**Physics**

If a sprinter accelerates from rest at a constant rate of 2.0m/s/s how fast will they be running after 4.0s?
*Wednesday, November 11, 2015 by phinigan*

**Physics**

A person of mass 81.7 kg escapes from a burning building by jumping from a window situated 28.9 m above a catching net.The acceleration of gravity is 9.8 m/s^2. If air resistance exerts a force of 123.1 N on him as he falls, determine his speed just before he hits the net. ...
*Wednesday, November 11, 2015 by Jordan*

**Physics**

A car’s velocity decreases at a constant rate from 22.0m/s to 10.0m/s over a period of 3.0s. –What is the car’s average acceleration?
*Wednesday, November 11, 2015 by phinigan*

**chemistry or physics**

What is the speed of light in scientific notation?
*Wednesday, November 11, 2015 by Brooke N*

**Physics**

A train speeds up from a speed of 5 meters per second to 15 meters per second, taking 15 seconds to do so. –Find the acceleration of the train.
*Wednesday, November 11, 2015 by phinigan*

**Physics**

A car accelerates uniformly at 3 m/s/s in order to overtake another car. If the initial speed was 30 m/s and the car accelerated until its speed was 40 m/s –For how long did it accelerate? –How much distance was covered in that time?
*Wednesday, November 11, 2015 by phinigan*

**physics**

A car is initially travelling at 30 m/s, which is above the speed limit. The driver sees a speed limit trap ahead and applies the brakes for 5 seconds, causing the car to slow down by 2m/s every second while the brakes are on. –How far does a car travel whilst the brakes ...
*Wednesday, November 11, 2015 by P*

**Physics**

A spaceship of mass 2.1×10^6 kg is cruising at a speed of 5.0×10^6 m/s when the antimatter reactor fails, blowing the ship into three pieces. One section, having a mass of 4.8×10^5 kg , is blown straight backward with a speed of 2.3×10^6 m/s . A second ...
*Wednesday, November 11, 2015 by Joseph*

**Physics**

A motorcyclist is trying to leap across a canyon by driving horizontally off a cliff (height= 60 m) at a speed of 25 m/s. The cycle strikes a cliff on the other side (height= 30 m) at a speed of 15 m/s. Find the work done by air resistance.
*Wednesday, November 11, 2015 by Daniela*

**Physics**

A 10kg mass is suspended as shown: i.gyazo[dotcom]/47dc49d5ec1eebe950472dba5f692e70.png (remove the brackets) What is the tension in the cord between points A and B? What is the tension in all of the cords? Thanks for the help, I just can't figure it out...
*Wednesday, November 11, 2015 by Amanda*

**Physics**

A car accelerates from rest with a uniform acceleration of 1.7m/s for 10secs., its acceleration then reduces by 0.3m/s for 20secs. of the motion it then maintains the speed attained for another 20secs. after which it decelerates to rest within 10secs. hence calculate the ...
*Wednesday, November 11, 2015 by Rakelly*

**Physics**

An object is traveling at a constant speed of 12.0 m/s when it slows to a stop. If it takes 10.0 m for the object to stop, what is the magnitude of its acceleration?
*Wednesday, November 11, 2015 by Anonymous*

**physics**

If there were no air resistance, with what speed would drops hit the Earth if they fell from a cloud 3881 m above the Earth’s surface? The acceleration of gravity is 10 m/s
*Wednesday, November 11, 2015 by Anonymous*

**Physics**

A car accelerates from rest with a uniform acceleration of 1.7m/s for 10 seconds, its acceleration then reduces by 0.3m/s for 20 seconds of the motion, it then maintains the speed attained for another 20 seconds after which it decelerates to rest within 10 seconds. Draw the ...
*Wednesday, November 11, 2015 by Kelly*

**physics**

It continues to fly along the same horizontal arc but increases its speed at the rate of 1.41 m/s.Find the magnitude of acceleration under these new conditions. Answer in units of m/s
*Wednesday, November 11, 2015 by Maria *

**physics**

An object of mass 2kg is pulled to the right w/a force of 20N. The force makes an angle of 20o w/ the displacement axis. If the interface is rough w/a coefficient of kinetic friction 0.3, what's the net force along the diaplacement axis?
*Wednesday, November 11, 2015 by Sam*

**Physics**

At a playground, a 22kg child plays on a slide that drops through a height of 2.1m. The child starts at rest at the top of the slide. On the way down, the slide does a nonconservative work of -371J on the child. What is the child's speed at the bottom of the slide?
*Wednesday, November 11, 2015 by Amanda*

**physics**

An apple (0.100 kg) is thrown vertically upward at a speed of [let x = any whole number between 10 and 20] m/s (from an arm 1.5 m off of the ground). What is the maximum height that the apple reaches? (g=9.8 m/s2)
*Wednesday, November 11, 2015 by devon*

**College Physics**

A 10 kg mass (initially at rest) is attached to a rope, which is wrapped about a thin-walled hollow cyclinder of diameter D = 50 cm and mass = 20 kg. After the 10 kg mass drops a distance of 1.4 m, what is the angular speed of the cylinder? What is the acceleration of the ...
*Wednesday, November 11, 2015 by Steve*

**AP Physics**

What is the minimum work needed to push a 1025 kg car 290 m up a 17.5° incline with zero friction?
*Wednesday, November 11, 2015 by -*

**AP Physics**

A car does 8.0 ✕ 104 J of work in traveling 2.7 km at constant speed. What was the average retarding force (from all sources) acting on the car?
*Wednesday, November 11, 2015 by -*

**Physics**

A) A 600 kg steel beam is supported by the two ropes shown in (Figure 1). Calculate the tension in the rope. Express your answer to two significant figures and include the appropriate units. B) The rope can support a maximum tension of 3200 N . Is this rope strong enough to do...
*Wednesday, November 11, 2015 by PSS*

**Physics**

Randy throws a tennis ball horizonally to hit a wall 20 m away. If the ball hits the wall 1.5s after it is thrown, what is the horizontal component of the balls velocity?
*Wednesday, November 11, 2015 by Dylan*

**Physics**

Air consists of molecules of several types, with an average molar mass of 28.95g. About how many molecules does an adult who inhales 0.50L of air at sea level take in? The answer should be 1.3x10^22
*Wednesday, November 11, 2015 by John*

**physics**

The potential energy of a pair of hydrogen atoms separated by a large distance x is given by U(x)=-C(subscript)6/x^6, where C_6 is a positive constant. What is the force that one atom exerts on the other? Is this force attractive or repulse? I've taken the derivative of ...
*Wednesday, November 11, 2015 by justin*

**College Physics**

A 10 kg mass (initially at rest) is attached to a rope, which is wrapped about a thin-walled hollow cyclinder of diameter D = 50 cm and mass = 20 kg. After the 10 kg mass drops a distance of 1.4 m, what is the angular speed of the cylinder? What is the acceleration of the ...
*Tuesday, November 10, 2015 by Steve*

**Physics**

Answer
*Tuesday, November 10, 2015 by Setual *

**Physics**

A 0.78 kg rock is whirled around in a flat circle at the end of a string of length 64 cm and a radial acceleration of 3.70 m/s^2 (a) What is the linear velocity of string? (b) what is the centripetal force acting on the rock? Vm= sqrt( grFs ) = sqrt( 9.8 m/s)(47.5m) (0.740) ?
*Tuesday, November 10, 2015 by rayanne*

**Physics**

Catching a wave, a 77-kg surfer starts with a speed of 1.2 m/s , drops through a height of 1.60 m , and ends with a speed of 8.5 m/s . How much nonconservative work was done on the surfer?
*Tuesday, November 10, 2015 by Ashlee*

**Physics**

Catching a wave, a 77-kg surfer starts with a speed of 1.2 m/s, drops through a height of 1.60 m, and ends with a speed of 8.5 m/s. How much nonconservative work was done on the surfer?
*Tuesday, November 10, 2015 by Amanda*

**Physics**

Two cars collide as shown in the figure. The yellow car is initially heading east and has a mass of 1000 kg. The red truck is initially heading north and has a mass of 2000 kg. The two vehicles collide, stick together, and veer off at a velocity of 16 m/s at a direction of 24 ...
*Tuesday, November 10, 2015 by David*

**Physics**

Two asteroids of equal mass collide as shown in the figure. After the collision, asteroid A’s trajectory is deflected by 30 degrees from its initial motion. Asteroid B is initially at rest and its final velocity makes a 45 degree angle with respect to the initial ...
*Tuesday, November 10, 2015 by GG*

**Physics**

A golf ball has a mass of 0.05 kg. It is initially at rest, but after being struck by a golf club it is given a speed of 30 m/s. The club and the ball are in contact for 2 ms (.002 seconds). a) What is the average force acting on the ball? b) What is the impulse of the net ...
*Tuesday, November 10, 2015 by Alvin*

**physics**

A puck (mass m1 = 2.20 kg) slides on a frictionless table as shown in the figure below. The puck is tied to a string that runs through a hole in the table and is attached to a mass m2 = 6.6 kg. The mass m2 is initially at a height of h = 6.6 m above the floor with the puck ...
*Tuesday, November 10, 2015 by John*

**physics**

A child of mass 52 kg jumps onto the edge of a merry-go-round of mass 170 kg and radius 1.9 m that is initially at rest as sketched in the figure below. While in the air (during her jump), the child's linear velocity in the direction tangent to the edge of the merry-go-...
*Tuesday, November 10, 2015 by John*

**math, physics**

A motorboat goes upstream on a river and covers the distance between two towns on the riverbank in 6 hours. It covers this distance downstream in 5 hours. If the speed of the stream is 1.5 km/h, find the speed of the boat in still water. [This problem is challenging.
*Tuesday, November 10, 2015 by sophie*

**physics**

Goku wants to visit Andromaeda galaxy which is 2 million light years away from earth. If it takes 30 years in the frame of the spaceship to travel to Andromeda from earth, what should be the speed of the spaceship? Assume that the spaceship travels at constant speed
*Tuesday, November 10, 2015 by Kitty*

**physics**

A fly of mass .2 g sits 12 cm from the center of a phonograph record revolving 331.3 rpm. a)What is the magnitude of the centripetal force on the fly?b)What is the minimum value of the coefficient of static friction between the fly and the record required to prevent the fly ...
*Monday, November 9, 2015 by Jenna*

**Physics**

A car starts from rest with an acceleration of 1.87 m/s^2 at the same time that a second car moving with a velocity of 29.2 m/s passes it. How far does the first car move before it overtakes the second car?
*Monday, November 9, 2015 by Frank William*

**Physics**

A girl with a 72.8 g yo-yo is swinging it in a horizontal circle at an angular velocity of 7.99 rad/s. If the string is tilted down at an angle of 17.1°, what must the length of the yo-yo string be? so i tried doing r = (0.0728)(7.99)^2/(9.8sin17.1 + 9.8cos17.1) i got 0....
*Monday, November 9, 2015 by UOIT*

**physics**

An electrostatic paint sprayer has a 0.200-m-diameter metal sphere at a potential of 25.0 kV that repels paint droplets onto a grounded object. What charge must a 0.100-mg drop of paint have to arrive at the object with a speed of 10.0 m/s?
*Monday, November 9, 2015 by carolyn*

**physics**

The drawing shows a skateboarder moving at 6.88 m/s along a horizontal section of a track that is slanted upward by 37.3 ° above the horizontal at its end, which is 0.741 m above the ground. When she leaves the track, she follows the characteristic path of projectile ...
*Monday, November 9, 2015 by John*

**Physics**

An 91.0 kg in-line skater does 3620 J of nonconservative work by pushing against the ground with his skates. In addition, friction does -615 J of nonconservative work on the skater. The skater's initial and final speeds are 2.70 m/s and 1.02 m/s, respectively. Part B ...
*Monday, November 9, 2015 by Amanda*

**Physics**

A 0.26-kg rock is thrown vertically upward from the top of a cliff that is 32 m high. When it hits the ground at the base of the cliff, the rock has a speed of 32 m/s . Part A Assuming that air resistance can be ignored, find the initial speed of the rock. Part B Find the ...
*Monday, November 9, 2015 by Amanda*

**Math**

Which of the following situations corresponds to the equation below? 1/3x + 8 = 18 2/3 Keneda is packing some suitcases to take on a cruise. The cruise line allows each guest to bring up to three pieces of luggage with a limit on total weight. So far, she has packed pounds ...
*Monday, November 9, 2015 by Wendy*

**Quick Physics Check**

2. Which of the following examples does not show projectile motion? A. a tennis ball bounces across the net B. a ball is thrown at a downward angle toward a target on the ground C. a feather drifts to the ground D. a horseshoe is pitched at a stake Is it C? 3. Which of the ...
*Monday, November 9, 2015 by Anonymous*

**Physics**

A 55-kg packing crate is pulled with constant speed across a rough floor with a rope that is at an angle of 41.0 ∘ above the horizontal. If the tension in the rope is 195 N , how much work is done on the crate by the rope to move it 3.0 mm ?
*Monday, November 9, 2015 by Amanda*

**physics**

Why do light(photons) have no mass
*Monday, November 9, 2015 by stephan*

**Physics**

You are installing a new spark plug in your car, and the manual specifies that it be tightened to a torque that has a magnitude of 45.8 N*m. Using the data in the figure below (L = 0.287 m and θ = 49.6°), determine the magnitude F of the force that you must exert on ...
*Monday, November 9, 2015 by Julia*

**physics**

A(n) 2153 kg car is coasting along a level road at 34.4 m/s. A constant braking force is applied, such that the car is stopped in a distance of 61.8 m. What is the magnitude of the braking force? Answer in units of N
*Monday, November 9, 2015 by colton*

**Physics**

The school bus slows from 60km/h to 40km/h when entering the scholl zone. a. Calculate the conversation of these speeds from km/h to m/s. b. Given that this change of speed occured over 8 seconds, calculate the average deceleration of the bus. My work... a.60/3.6=17m/s 40/3.6=...
*Monday, November 9, 2015 by Ronnie*

**Physics**

a uniform pole 20ft long ang weighing 50lbs is used to carry a load of 180lbs.Two men,one supporting twice as much as the other support the pole to keep it in a horizontal position.How far from the center of the pole should the load be hung.?
*Monday, November 9, 2015 by zyrinxlee*

**Physics**

An experimental model rocket has a mass of 0.054kg. The fuel that was used in one test had 215J of chemical potential energy. When the rocket reached an altitude of 119m, it was travelling at 48m/s and still rising. With what efficiency did the rocket convert chemical ...
*Monday, November 9, 2015 by Annie*

**AP Physics**

A large box has a mass of 500kg and the coefficient of static friction for the box and the floor is 0.45, and the coefficient of kinetic friction is 0.30. a. What is the minimum horizontal force needed to get the box moving? b. If you continue to push with that force, what ...
*Sunday, November 8, 2015 by Anna*

**AP Physics**

A mystery surprise box is sliding down a ramp at a constant speed. The box has a mass of 55.0kg and the ramp makes a 40.0œ angle with the horizontal. What is the coefficient of kinetic friction between the box and the ramp? Please help asap. Thank you.
*Sunday, November 8, 2015 by Anna*

**Simple algebra/Physics problem**

A proton, moving with a velocity of vi, collides elastically with another proton that is initially at rest. Assuming that after the collision the speed of the initially moving proton is 2.90 times the speed of the proton initially at rest, find the following. (a) the speed of ...
*Sunday, November 8, 2015 by PersonWhoNeedsHelp*

**Physics**

A stone weighs 34.0 N. What force must be applied to make it accelerate upward at 4.00 m/s2?
*Sunday, November 8, 2015 by Anonymous*

**physics**

A 40 N force is applied at an angle of 30o to the horizontal to pull a 6 kg box along the floor. If the coefficient of friction between the box and floor is 0.3.The box initially at rest moves a horizontal distance of 5m. What is the speed of the box when it reaches 5m? No ...
*Sunday, November 8, 2015 by Prince*

**physics**

Three people attempt to hold a heavy sign in place. Abby pulls directly upwards (in the middle) with 140 N of force. Joe is ob Abby's left and pulls at a 30.0° to Abby's rope with a force of 180 N. Henry is on Abby's right and pulls at a 30.0° to Abby's...
*Sunday, November 8, 2015 by Heather*

**Physics**

A stone weighs 34.0 N. What force must be applied to make it accelerate upward at 4.00 m/s2?
*Sunday, November 8, 2015 by Anonymous*

**physics**

A force is applied to a 2.9 kg mass and produces 2.7 m/s 2 acceleration. What acceleration would be produced by the same force applied to a 6.2 kg mass? Answer in units of m/s 2 .
*Sunday, November 8, 2015 by chris*

**Physics**

Two newly discovered planets follow circular orbits around a star in a distant part of the galaxy. The orbital speeds of the planets are determined to be 36.0 km/s and 50.6 km/s. The slower planet's orbital period is 7.78 years. (a) What is the mass of the star? (b) What ...
*Sunday, November 8, 2015 by Hannah*

**Physics**

A "swing" ride at a carnival consists of chairs that are swung in a circle by 11.5 m cables attached to a vertical rotating pole, as the drawing shows. Suppose the total mass of a chair and its occupant is 204 kg. (a) Determine the tension in the cable attached to ...
*Sunday, November 8, 2015 by Hannah*

**Physics "Simple" Energy Problem**

Jonathan is riding a bicycle and encounters a hill of height 6.70 m. At the base of the hill, he is traveling at 5.00 m/s. When he reaches the top of the hill, he is traveling at 3.00 m/s. Jonathan and his bicycle together have a mass of 77.6 kg. Ignore friction in the bicycle...
*Sunday, November 8, 2015 by PersonWhoNeedsHelp*

**physics **

An airplane travels 3900 km at 810 km/h, and then encounters a tailwind that boosts its speed to 950 km/h for the next 3000 km. What was the average speed of the plane for this trip? 3900+3000 6900 6900/8 862.5
*Sunday, November 8, 2015 by jesse*

**Physics**

A proton, moving with a velocity of vi, collides elastically with another proton that is initially at rest. Assuming that after the collision the speed of the initially moving proton is 2.90 times the speed of the proton initially at rest, find the following. (a) the speed of ...
*Sunday, November 8, 2015 by PersonWhoNeedsHelp*

**physics**

Alice has a mass of 70.0 kg and her car has a mass of 1000.0 kg. Alice is sitting in parked car on the side of the road. The magnitude of the normal force exerted by the road on her car is? (use g = 9.81 m/s2)
*Sunday, November 8, 2015 by Sami*

**Physics**

A marble and a cube are placed at the top of a ramp. Starting from rest at the same height, the marble rolls without slipping and the cube slides (no kinetic friction) down the ramp. Determine the ratio of the center-of-mass speed of the cube to the center-of-mass speed of the...
*Sunday, November 8, 2015 by Rob*

**Physics**

Two buckets of sand hang from opposite ends of a rope that passes over an ideal pulley. One bucket is full and weighs 110 N ; the other bucket is only partly filled and weighs 65 N . You release the lighter bucket and the heavier one descends. What is the tension in the rope?
*Sunday, November 8, 2015 by Luke*

**physics**

The bird perched on the swing shown below has a mass of 41.6 g, and the base of the swing, y = 7.88 cm below the hook, has a mass of 147 g. The swing and bird are originally at rest, and then the bird takes off horizontally at 1.94 m/s. How high will the base of the swing rise...
*Sunday, November 8, 2015 by Jackson*

**physics**

A spring and mass system are oscillating with an amplitude of 5.4 cm. The spring constant is 166 N/m and the mass is 540 g. Find the mechanical energy of the system
*Sunday, November 8, 2015 by diana*

**physics**

a body travels from rest with acceleration 8ms find its velocity when it has covered a distance of 100m
*Sunday, November 8, 2015 by ezekel ayuba*

**physics**

an object of mass 10kg moves in a circle of radius 13m of uniform speed of 43m\s a) calculate the angular velocity b) the centripetal force
*Sunday, November 8, 2015 by cynthia*

**physics**

Lunar astronauts placed a reflector on the Moon’s surface, off which a laser beam is periodically reflected. The distance to the Moon is calculated from the round trip time. The taken for the laser pulse to travel there and back again can be measured to 0.1 ns. What ...
*Sunday, November 8, 2015 by carolyn*

**physics**

A heart defibrillator passes 10.0 A through a patient’s torso for 5.00 ms in an attempt to restore normal beating. Find the temperature increase caused in the 8.00 kg of affected tissue if all the energy heats up the tissue with a specific heat capacity of 3000 J kg-1 K-1.
*Sunday, November 8, 2015 by carolyn*

**physics**

Alkaline batteries have the advantage of putting out constant voltage until very nearly the end of their life. How long will an alkaline battery rated at 1 A ⋅ h and 1.58 V keep a 1 W flashlight bulb burning?
*Sunday, November 8, 2015 by carolyn*

**physics**

two force vectors, f1 18N at 60 degree above the positive axis and F2 6.5N at 45 degree below the positive axis, are applied to a particle at the origin. what third force f3 would make the net force on the particle equal to zero
*Sunday, November 8, 2015 by Anonymous*

**Physics**

A ball is dropped from a building, after 2 sec another ball is thrown downward. After 6 sec the second ball overtook the first ball. Is the second ball has greater acceleration than the first ball? Explain.
*Sunday, November 8, 2015 by Mike*

**ap physics**

The acceleration due to gravity on the moon has a magnitude of 1.62 m/s. deal with a placekicker kicking a football. Assume that the ball is kicked on the moon instead of on the earth. Find (a) the maximum height H and (b) the range that the ball would attain on the moon.
*Sunday, November 8, 2015 by Anonymous*

**physics**

An object has an initial velocity of 2.25 m/s at 57.2 degrees. An acceleration of 133.4 m/s/s at 59.5 degrees is applied. What was the final speed after the object has a displacement of 8.8 m at 33.5 degrees?
*Saturday, November 7, 2015 by EB*

**physics**

An object has an initial velocity of 3.87 m/s at 40.3 degrees. 8.35 seconds later it is moving at 41.1 m/s at an angle of 26.5 degrees. What acceleration caused this change in velocity? (Give your answer in terms of the +x-axis, in degrees)
*Saturday, November 7, 2015 by EB*

**physics**

After a constant acceleration of 2.2 m/s/s at 16 degrees above the +x-axis is applied by the motors of a boat for 8 seconds, the boat is moving at 61.45 m/s at 43.5 degrees above the +x-axis. What was the displacement of the boat during this time? (Give your answer in terms of...
*Saturday, November 7, 2015 by EB*

**physics**

After a constant acceleration of 2.1 m/s/s at 31.7 degrees above the +x-axis is applied by the motors of a boat for 7.75 seconds, the boat is moving at 59.1 m/s at 43 degrees above the +x-axis. What was the initial velocity of the boat? (Give your answer in terms of a positive...
*Saturday, November 7, 2015 by EB*

**physics**

In a shipping company distribution center, an open cart of mass 55.0 kg is rolling to the left at a speed of 5.30 m/s (see the figure (Figure 1) ). You can ignore friction between the cart and the floor. A 18.0 kg package slides down a chute that is inclined at 37 ∘ from...
*Saturday, November 7, 2015 by malakai*

**physics**

Alkaline batteries have the advantage of putting out constant voltage until very nearly the end of their life. How long will an alkaline battery rated at 1 A ⋅ h and 1.58 V keep a 1 W flashlight bulb burning?
*Saturday, November 7, 2015 by carolyn*

**Physics**

Lunar astronauts placed a reflector on the Moon’s surface, off which a laser beam is periodically reflected. The distance to the Moon is calculated from the round trip time. The taken for the laser pulse to travel there and back again can be measured to 0.1 ns. What ...
*Saturday, November 7, 2015 by carolyn*

**physics**

A heart defibrillator passes 10.0 A through a patient’s torso for 5.00 ms in an attempt to restore normal beating. Find the temperature increase caused in the 8.00 kg of affected tissue if all the energy heats up the tissue with a specific heat capacity of 3000 J kg-1 K-1.
*Saturday, November 7, 2015 by carolyn*

**Physics**

The propeller blades of an airplane are 2.4 m long. The plane is getting ready for takeoff, and the propeller starts turning from rest at a constant angular acceleration. The propeller blades go through two revolutions between the fifth and the seventh second of the rotation. ...
*Saturday, November 7, 2015 by John*

**general physics question**

Whenever I read my science textbooks, they always say that "electrons were fired" or "stream of electrons were fired to the target" during an experiment my question is, how to they generate a stream of electrons to fire in a line?? sorry if this is a dumb ...
*Saturday, November 7, 2015 by Anonymous*

**physics**

A 22 kg child is riding a playground merry-go-round that makes 40 revolutions in 60 seconds. Determine the magnitude of force (in Newtons) necessary to make the child stay on the merry-go-round if she is 1.25m from its center.
*Saturday, November 7, 2015 by edson*

**physics**

the speed of train is reduced from 60km/h at the same time as it travel a distance of 450m if retardation is uniform find how much further it will travel approx befor coming rest?
*Saturday, November 7, 2015 by tarique*

**physics**

Two workers are sliding 330 kg crate across the floor. One worker pushes forward on the crate with a force of 410 N while the other pulls in the same direction with a force of 240 N using a rope connected to the crate. Both forces are horizontal, and the crate slides with a ...
*Friday, November 6, 2015 by yahya*