## Physics Questions and Answers

Physics

### How are impulse and momentum applied in an egg drop challenge? The challenge was to construct something protective...

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...

Physics

### What is the mass of air in a room measuring 5m X 10m X 10m?

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...

Physics

### Why is a parallel circuit arrangement best for house wiring?

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...

Physics

### What is the magnitude of the acceleration of the chair, and the magnitude of the normal force acting on the chair in...

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...

Physics

### You throw a basketball straight up into the air. Describe what happens to the kinetic energy and the gravitational...

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...

Physics

### Why is the current flow greater in a parallel circuit than it is in a series circuit?

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...

Physics

### In the context of conservation of energy what effect does friction have on kinetic energy and gravitational potential...

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,...

Physics

### What happens to a object's kinetic energy if its speed changes, for example it becomes double or triple.

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...

Physics

### What is the illuminance (in lm/m^2) on a desktop if the lamp is 0.9 m above it? The equation of the illuminance, E,...

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

Physics

### The position vector of a particle is given by r(t)=t^3*i+t^2*j. What are it's velocity speed and acceleration when t=2

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...

Physics

### A wire has a resistance R. If the length of a wire is doubled and the radius is doubled, what is the new resistance...

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...

Physics

### What is the formula for pressure?

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...

Physics

### A person is standing on a scale in a elevator accelerating downward. compare the reading on the scale to the person's...

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...

Physics

### Can an object have kinetic energy and potential energy at the same time?

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...

Physics

### A bullet is fired horizontally out of a gun at the same time another is dropped from the end of the barrel. The one...

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...

Physics

### Are kinetic energy and height inversely proportional to each other or directly proportional to each other? Why?

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...

Physics

### For a 21.1 kg rock is on the edge of a 96.2 m cliff what are the following: The potential energy does the rock...

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...

Physics

### Which are the most conductive and least conductive metals?

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...

Physics

### A racing car has a mass of 1900 kg. The acceleration of gravity is 9.8 m/s2 . What is its kinetic energy if it has a...

A body in motion has kinetic energy. Kinetic energy can be due to linear motion as well as angular motion. We don't need the acceleration due to gravity to determine the kinetic energy of the car....

Physics

### Explain how to measure the volume of an irregular shaped object if it floats in water.

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...

Physics

### A 1.98 kg ball is attached to a ceiling by a 2.1 m long string. The height of the room is 5.95 m. The acceleration of...

Thte way you have worded this, the ball is below the ceiling, so the potential energy with respect to the ceiling is negative. PE = mgh, and since the zero position is the ceiling, the potential...

Physics

### Why do heavier things fall faster than lighter things if dropped from a certain height ? related to gravitational force.

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...

Physics

### Density Of Mercury

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...

Physics

### What is the final temperature? A 23.8 g silver ring (cp = 234 J/kg·°C) is heated to a temperature of 82.2°C and then...

A 23.8 g silver ring (cp = 234 J/kg*C) is heated to a temperature of 82.2 C and then placed in a calorimeter containing 5.32*10^-2 kg of water at 24.0 C. The calorimeter is not perfectly insulated...

Physics

### Unbalanced forces can cause an object to do three things. What are they?

Forces are considered balanced when all of the combined forces lead to no change in the motion of the object. For example, when a book is sitting on a table, the force of gravity is pushing...

Physics

### A 145g baseball is thrown with a speed of 25m/s . How much work was done on the baseball to reach this speed if it...

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...

Physics

### What is the height of the tower in the following case? A visitor to a lighthouse wishes to determine the height of...

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...

Physics

### A small object with a momentum of magnitude 5 kg*m/s approaches head-on a large object at rest. The small object...

The initial momentum of the small object is 5 kg*m/s towards the larger object that is at rest. After collision, the small object bounces back with a momentum that has a magnitude or 4 kg*m/s. As...

Physics

### A ray of light strikes a mirror at an angle of 30 degree to the mirror surface. What is the angle of reflection?

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...

Physics

### PHYSICS help If a metal wire has its length doubled and its diameter tripled, by what factor does its Young's modulus...

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....

Physics

### How can a large force result in small power?

Power is defined as the ratio of work per time, or 1. Power = Work/Time Work is defined as Force times Displacement, or 2. Work = Force * Displacementso therefore3. Power = (Force * Displacement) /...

Physics

### The density of ice is 917 kg/m^3. what fraction of the volume of a piece of ice will be above water, when floating in...

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...

Physics

### A convex mirror has a focal length of −27 cm. What is the object distance if the image distance is −16 cm?

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...

Physics

### How far will the car slide once the brakes are applied and it comes to a stop in the following case: A 14,700 N car...

The car is initially traveling at 25 m/s. When the brakes are applied there is a resistive force that leads to a decrease in the velocity of the car and it eventually comes to a stop. The weight of...

Physics

### How much force is exerted by the atmosphere on 10.8 km^2 of land at sea level?

The pressure acting on a surface is determined by the force acting on a unit area of the surface. At sea level the standard pressure exerted by the atmosphere or 1 atm = 101325 Pa. Pascal is a unit...

Physics

### How are energy, time, and power related?

A physical system that can do work on other physical systems has an amount of energy that is equal to the work that can be done. For example, a compressed spring can do work on another body when it...

Physics

### What is the maximum height the ball reaches? A ball is thrown vertically upward from the roof of a 64 foot tall...

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...

Physics

### Is a hockey stick used as lever? What kind of lever is it?

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...

Physics

### ROTATION: A solid ball of mass 2.6 kg and diameter 15cm is rotating about its axis at 80 rev/min. A. What is its...

This needs the basic understanding of rotational dynamics. Kinetic energy of a rotating mass is KE = (I * w^2)/2 where I is the moment of inertia and w (omega) is the rotational velocity in...

Physics

### Calculate the angle of projection, with the horizontal, for a projectile for which the maximum height is equal to the...

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...

Physics

### What is the effect on the vertical height of the mercury column in a barometer of a) using a wider glass tube, b)...

The height of mercury above the bowl in a barometer is a measure of the pressure of air pushing on the mercury in the bowl. The mass of the mercury above the bowl times the force of gravity is...

Physics

### What is the horizontal distance traveled by the hammer from the time it leaves the roof to the time it hits the...

The worker on the roof of the house drops his 0.83kg hammer, which slides down the roof at constant speed of 8.55m/s. The angle made by the roof with the horizontal is 21 degrees and its lowest...

Physics

### A 0.160 kg hockey puck starts from rest and reaches a speed of 22 m/s when a hockey stick pushes on it for 1.2 m...

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...

Physics

### Water in an electric kettle connected to a 220 V supply took 5 minutes to reach its boiling point. How long would it...

Water absorbs heat in the electric kettle and increases in temperature. It soon reaches the boiling point once enough heat has been absorbed. The heat produced in the electric kettle is due to the...

Physics

### Water has a density of 1000kg/m^3; what does this mean? What is its density in g/cm^3?

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...

Physics

### Two balls, each with a mass of 0.813 kg, exert a gravitational force of 8.38 x 10^-11 N on each other. How far apart...

The formula for gravitational attraction is Fg = (Gm1m2)/r^2 In this formula, G is the Universal Gravitational Constant while m1 and m2 are the masses of the two bodies. R is the distance of...

Physics

### A rope pulls a 2.0 kg bucket straight up, accelerating it from rest at 2.2 m/s^2 for 3.0 s. 1. Calculate the work...

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...

Physics

### At what velocity should he throw the bag and how far from the house is he standing when he throws the bag in the...

I think justaguide meant to use V*sin60 in the first calculation so all the values are vertical ones. At the top of the trajectory when it "just" gets into the window it will have 0 vertical...

Physics

### Define the terms image distance and object distance as they apply to reflection in a plane mirror.

I hope you know that when the rays from an object fall on any mirror (concave convex or plane), an image is formed. In case of a place mirror, the object is placed in front of the mirror and image...

Physics

### A force of 200 N acts on an area of 4 m^2. What is the pressure and what would be the pressure if the same force...

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...

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