Physics Questions and Answers

Physics

A 145 g baseball is thrown with a speed of 25 m/s. When the thrower picks up the ball it is at rest. When it leaves the hand of the person that is throwing the ball it has a speed of 25 m/s. An...

Latest answer posted March 26, 2012 11:26 am UTC

2 educator answers

Physics

In order to find the answer to this question, you need to know the following equation: m = dv Where m is mass, d is density, and v is volume. In this case, you are looking for mass, you have...

Latest answer posted December 20, 2009 1:19 am UTC

1 educator answer

Physics

Impulse is the change in momentum of an object. There are two impulses that your egg design will have to deal with. The first impulse is from the drop itself. Its momentum will increase due to the...

Latest answer posted April 21, 2013 5:52 pm UTC

1 educator answer

Physics

For a potential difference V across a resistor R, the current I that flows through the resistor is given by Ohm's law as I = V/R As current is inversely proportional to resistance, for the same...

Latest answer posted February 29, 2012 1:47 am UTC

1 educator answer

Physics

In a house, there are many electrical appliances that have to run independent of each other. If one appliance is turned on or off it should not affect the other appliances. This is not possible if...

Latest answer posted February 29, 2012 2:01 am UTC

1 educator answer

Physics

We have the position vector given in terms of time t. r(t) = t^3*i + t^2*j To find the velocity vector we have to differentiate r(t) with respect to time. r'(t) = 3t^2*i + 2t*j The vector...

Latest answer posted March 22, 2011 3:25 am UTC

1 educator answer

Physics

Rearranging terms, E ( 4(3.1416)d^2 ) = P, so E ( 4(3.1416)[.9m^2] ) = 1200 lm E ( 12.57 [.81m^2] ) = 1200 lm E (10.17m^2) = 1200 lm E = 1200 lm / 10.17 m^2 E = 118 lm/m^2

Latest answer posted June 11, 2011 1:30 am UTC

1 educator answer

Physics

When the basketball is thrown up an initial velocity is imparted to it. This gives the ball a kinetic energy equal to (1/2)*m*v^2 where m is the mass of the ball and v is the velocity with which it...

Latest answer posted December 2, 2012 9:34 am UTC

1 educator answer

Physics

They both hit the ground at the same time. So your answer is C. Gravity works on the bullets just the same regardless of velocity. The bullets have to be the same calibre and weight for this to...

Latest answer posted June 1, 2009 8:55 am UTC

1 educator answer

Physics

The electrical conductivity of a metal has the SI units Siemens/meter. This is a reciprocal of the resistivity that is expressed in terms of ohm*m. Electrical conductivity of a metal is not the...

Latest answer posted November 4, 2011 1:41 pm UTC

1 educator answer

Physics

The law of conservation of energy states that the total energy in an isolated system does not change. It may change form, for example mechanical energy may get converted to thermal energy,...

Latest answer posted November 19, 2011 12:10 pm UTC

1 educator answer

Physics

The safe answer is C. See below why it could also be D: The best way to think of weight is this: weight is the measurement of resistance of a given mass to falling. On the earth, everything that...

Latest answer posted December 12, 2009 12:10 pm UTC

2 educator answers

Physics

The displacement of water is an excellent way to measure the volume of a solid provided that the solid does not dissolve in water and that it does not float. If the object floats then it will not...

Latest answer posted September 22, 2012 3:55 am UTC

1 educator answer

Physics

At a height h, the gravitational potential energy P of an object with mass m is given by the relation P = m*g*h. If the object is considered to be a closed system, it is assumed that there is no...

Latest answer posted November 21, 2011 9:27 am UTC

1 educator answer

Physics

A man in a metallic cage is not affected even when the cage is highly charged due to what is known as the Faraday cage effect. In a state of equilibrium, charges are as far from each other as...

Latest answer posted September 8, 2011 1:16 am UTC

1 educator answer

Physics

The resistance of a resistor is given by the formula `R = rho*l/A ` where `rho` is the resistivity of the material the resistor is made of, l is the length of the resistor and A is the...

Latest answer posted April 3, 2013 3:09 am UTC

1 educator answer

Physics

The formula for pressure is P = F/A In this equation, P stands for pressure while F stands for force and A stands for area. Pressure is typically measured in a unit called the Pascal. So what this...

Latest answer posted December 24, 2009 2:12 pm UTC

1 educator answer

Physics

The ball is thrown upwards at 96 ft/s from the roof of a building which is 64 foot tall. The height of the ball after t seconds is given by the function: s(t) = 64 + 96t - 16t^2 To find the maximum...

Latest answer posted February 22, 2011 2:01 pm UTC

1 educator answer

Physics

The angle of projection for which the maximum height of the projectile is equal to the horizontal range has to be determined. Let the required angle of projection be A and object is projected at V...

Latest answer posted February 16, 2012 10:29 am UTC

1 educator answer

Physics

The kinetic energy of an object with mass m and which has a speed of v is given by (1/2)*m*v^2. The change in the kinetic energy of the object as the speed changes is proportional to the square of...

Latest answer posted March 26, 2012 1:29 pm UTC

1 educator answer

Physics

Most of the time, people ask this question with the idea of a Newtonian "feather vs. bowling ball" concept in mind. Based on those terms, the typical answer is correct: two objects will fall at the...

Latest answer posted July 11, 2014 4:34 am UTC

3 educator answers

Physics

To determined the height of the tower a pendulum is created by tying a rock to a thread and hanging it from the ceiling of the tower. The period of the pendulum us found to be 9.18 s. The period of...

Latest answer posted February 13, 2012 11:38 am UTC

1 educator answer

Physics

The Young's modulus is a constant for metals in the range of values of stress for which Hooke's law is valid. It can be determined by the relation: Young's modulus= Tensile Stress/ Tensile Strain....

Latest answer posted November 18, 2010 7:39 pm UTC

1 educator answer

Physics

The gravitational potential energy of a body placed at a height h is given by PE = m*g*h where m is the mass of the body and g is the acceleration due to gravity. The mass of the rock is 21.1 kg...

Latest answer posted February 29, 2012 12:35 pm UTC

1 educator answer

Physics

When a body is placed in a fluid, there is an upward force exerted on the body that is equal to the weight of the fluid displaced by it as it sinks into the fluid. When this force is equal to the...

Latest answer posted June 2, 2012 3:14 pm UTC

1 educator answer

Physics

The answer is D. This can be easily determined by using the formula for linear expansion due to temperature (or linear thermal expansion). This formula is stated as change in length = alpha times...

Latest answer posted December 10, 2009 10:51 pm UTC

1 educator answer

Physics

The term "relative density" means the same as "specific gravity." It is a measure of how dense one thing is when compared to a given reference. The reference is usually water. With respect to...

Latest answer posted December 15, 2009 11:13 am UTC

1 educator answer

Physics

This is because of the amount of force that is put on your foot and the area over which the force is applied. Since pressure = force/area, the same force on a smaller area means more pressure....

Latest answer posted December 22, 2009 12:24 pm UTC

1 educator answer

Physics

Yusef pushes the chair of mass 45 kg across a carpeted floor with a force of magnitude 144 N directed 35.0 degrees below the horizontal. The magnitude of the frictional force between the carpet...

Latest answer posted February 27, 2012 1:24 am UTC

1 educator answer

Physics

The energy of a quantum of light or a photon is given by the formula E = h*nu = h*c/lambda, where nu is the frequency of the light, lambda is the wavelength, c is the speed of light and h is the...

Latest answer posted March 12, 2011 11:20 am UTC

1 educator answer

Physics

If I understand this question correctly, the angle of reflection should be 30 degrees with respect to the mirror as well. The angle of the incoming ray and the angle of the ray that is reflected...

Latest answer posted March 31, 2010 10:55 pm UTC

1 educator answer

Physics

The rope pulls the 2.0 kg buckets vertically upwards accelerating it from rest at 2.2 m/s^2 for 3 seconds. In 3 seconds, the distance traveled by the bucket is equal to s = u*t + (1/2)*a*t^2. Here...

Latest answer posted November 28, 2012 9:08 am UTC

1 educator answer

Physics

A hockey stick is used as a lever. When you hold a hockey stick, the hand with which you hold the stick at the top end serves as the fulcrum. The other hand with which you catch the stick in the...

Latest answer posted November 10, 2011 3:04 pm UTC

1 educator answer

Physics

The hockey puck has a mass 0.16 kg. It starts from rest and reaches a speed of 22 m/s, during which the distance traveled is 1.2 m. Initially the puck has no kinetic energy. After 1.2 m the kinetic...

Latest answer posted December 2, 2012 9:24 am UTC

1 educator answer

Physics

The following formula relates object distance, image distance, and focal length for convex mirrors: 1/(focal length) = 1/(object distance) + 1/(image distance) or 1/fo = 1/do + 1/di The image...

Latest answer posted May 18, 2011 7:52 am UTC

1 educator answer

Physics

When two resistors with resistance R1 and R2 are connected in parallel, the equivalent resistance of the configiration is given by 1/R = (1/R1 + 1/R2). And for two resistors R1 and R2 connected in...

Latest answer posted January 3, 2012 2:53 pm UTC

1 educator answer

Physics

Yes, an object can have both of these at the same time. Potential energy is energy that is stored in an object. Kinetic energy is the energy that is associated with motion. So what you have to...

Latest answer posted November 23, 2009 11:53 am UTC

1 educator answer

Physics

The pressure would be doubled if the same force acted on half the area. The pressure in the first scenario is 50 N/m^2 while the pressure in the second scenario is 100 N/m^2 The way you get this is...

Latest answer posted February 1, 2010 1:26 pm UTC

1 educator answer

Physics

The meaning of the original statement is that if you have a cubic meter of water (an amount of water that is one meter in height, one meter in width, and one meter in depth), that amount of water...

Latest answer posted December 15, 2009 12:02 am UTC

1 educator answer

Physics

As an airplane flies, the speed of air passing over the top of the wing is higher than the speed at which air flows below the wing. This creates a differential in the pressure above and below the...

Latest answer posted November 28, 2013 5:25 pm UTC

1 educator answer

Physics

Two tugboats pull a disabled supertanker. Each tugboat exerts a constant force of 1.50 X 10^6 N, one at an angle 15.0 degrees west of north, and the other at an angle 15.0 degrees east of north, as...

Latest answer posted March 8, 2012 12:44 am UTC

1 educator answer

Physics

The wall is made of forty 2.0 kg blocks each 20 cm thick. They are arranged in 4 rows one on top of the other each with 10 blocks. One row can be considered to be a single object of mass 10*2 = 20...

Latest answer posted December 2, 2012 9:16 am UTC

1 educator answer

Physics

The 66 kg skier slides down a hill 25 m high. The potential energy of the skier at the top of the hill that has a height of 25 m is given by PE = m*g*h = 66*9.8*25. At the bottom of the hill all...

Latest answer posted April 3, 2012 11:16 am UTC

1 educator answer

Physics

Remember we have the expressions: `E = A * (dB)/(dt)` `A = pi r^2` `E = pi r^2 (dB)/(dt)` where: A = area of the coil r = radius = diameter/2= 10.2/2 = 5.1 cm = 0.051 m db = change in magnetic...

Latest answer posted April 15, 2013 5:35 am UTC

1 educator answer

Physics

The ball rolls off the top of a stairway horizontally with a velocity of 4.5m/s. Each step is 0.2m high and 0.3m wide. Let the ball land on the nth step. The horizontal distance covered by the ball...

Latest answer posted July 17, 2012 3:36 pm UTC

1 educator answer

Physics

Refraction is the phenomenon of the "bending" of rays of light as they pass the boundary between two media, for example, air and water. It happens because the light propagates with different speeds...

Latest answer posted June 21, 2017 2:14 am UTC

2 educator answers

Physics

When a spring is extended or compressed from its equilibrium length, the change in length is related to the force applied by the relation F = -kx, where F is the force applied, k is the spring...

Latest answer posted February 23, 2011 10:06 pm UTC

1 educator answer

Physics

According to Ampere's law, the force between two wires carrying a current I1 and I2 and which are separated by a distance r is given as F= 2*K*I1*I2 / r, where K is a constant. In the problem, when...

Latest answer posted December 28, 2010 6:23 pm UTC

1 educator answer

Physics

It is give that a block placed on an inclined plane accelerates at 3.6 m/s^2 down the plane. The angle of inclination is 24.0 degrees. The coefficient of kinetic friction k needs to be determined....

Latest answer posted November 28, 2011 11:04 am UTC

1 educator answer

Physics

One major problem with intrasolar and interstellar communication is the vast distances involved. On Earth, radio communication is all-but instantaneous, because radio waves travel at the speed of...

Latest answer posted October 29, 2012 9:47 pm UTC

1 educator answer

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