You are arguing over a cell phone while trailing an unmarked police car by 25.0 m; both your car and the police car are traveling at 110 km/h. Your argument diverts your attention from the police car for 2.0 s (long enough for you to look at the phone and yell,“I won't do that!”). At the beginning of that 2.0 s, the police officer begins braking suddenly at 5.20 m/s². (a) What is the separation between the two cars when your attention finally returns? Suppose that you take another 0.400 s to realize your danger and begin braking. (b) If you too brake at 5.20 m/s², what is your speed when you hit the police car?

The position of a 50 g oscillating mass is given by x(t)=(2.0cm)cos(10t−π/4), where t is in s. If necessary, round your answers to three significant figures. Determine:

amplitude= 2cm

period= 0.628s

spring constant =5 N/m

phase constant= -0.785 rad

find initial coordinate of the mass and the initial velocity.

A ring of charge with radius R = 2.5 m is centered on the origin in the x-y plane. A positive point charge is located at the following coordinates: x = 17.1 m y = 3.8 m z = -16.3 m The point charge and the total charge on the ring are the same, Q = +81 C. Find the net electric field along the z-axis at z = 4.5 m.

E_{net,x =}

E_{net,y =}

E_{net,z =}

there's a triangular prism with sides 8 cm, 10 cm, and 5 cm made out of material of n = 1.9 is submerged in an aquarium of water with n = 1.333. A ray of light strikes the 8 cm long side precisely in the middle and at 24 degrees relative to the normal. Work out all the angles that you need to work out and calculate the angle that the ray emerges at. (this might take the law of sines or the law of cosines to do.)

the explanation is perfectly understandable

please write in 2 paragraphs for each concepts.. " The yo-yo works on two principles, (i) conservation of energy and (ii) Torque equals the product of Mass moment of Inertia of the disk in yo-yo toy and it's angular acceleration".

When a person inhales, air moves down the bronchus (windpipe) at 15 cm/s. The average flow speed of the air doubles through a constriction in the bronchus. Assuming incompressible flow, determine the pressure drop in the constriction.

The electric field midway between two equal but opposite point charges is 567 N/C , and the distance between the charges is 16.0 cm.

a)What is the magnitude of the charge on each?

As defined in Chapter 7, the work done by a force on an object is equal to the force times the displacement times the cosine of the angle between the force and displacement vectors (W=F·d cos(θ)).
Suppose you are supporting a 1.56-kg block. What is the gravitational force (magnitude and direction) acting on the block?

If you lower the block a distance of 0.208 m, what is the work done by the gravitational force as you lower the block?

What is the value of the angle θ (in degrees – do not enter units)?

What is the change in the gravitational potential energy as you lower the block 0.208 m? (If the potential energy increases, the answer should be positive. If the potential energy decreases, the answer should be negative.)

Let’s switch gears and ask about the electrical force on a charged object. Suppose you have a region where the electric field has a magnitude of 23.1 N/C, the field points straight down, and the field is uniform (ie., the magnitude and direction are the same everywhere in this region). You place an object which has a charge of +0.251 C in this field. What is the magnitude and direction of the electric force acting on the object?

Suppose you lower the object a distance 0.208 m (in the same direction the field is pointing). What is the work done by the electrical force as you lower the block?

What is the change in electric potential energy as you lower the object 0.208 m? (If the electric potential energy increases, the answer should be positive. If the electric potential energy decreases, the answer should be negative.)

This discussion is closed.

A tower worker at the top of a wind turbine tower is letting down a small broken part of mass 4.3 kg tied to a practically massless rope.

The top of the tower is 14.4m above the ground, and the wind is blowing at 6.3 m/s at the top of the tower and decreases linearly with height to 1.7 m/s at the ground.

She is letting the rope slide thru her leather gloves at a rate of 0.30 m/s, and the friction between the rope and her gloves is making the gloves warm. What power is being

dissipated as heat where rope is sliding on the gloves?

In this problem, consider electrostatic forces only. In the figure, there is a particle of charge +Q at x = 0, and there is a particle of charge +16Q at x = +4a. You are going to bring in a third particle, with a charge of ?4Q, and place it at an appropriate spot on the x-axis. Use Q = 60.0 ? 10^?6C, and a = 40.0 cm. Also, use k = 9.00 ? 10⁹ N · m²/C².

(a)First, place the particle of charge ?4Q at the correct location so that the +Q charge experiences no net force because of the other two charged particles. In that situation, calculate the magnitude of the force that just one of the other charged particles exerts on the +Q charge.

(b)Instead, at what location on the x-axis would you place the particle of charge ?4Q so that the +16Q charge experiences no net force because of the other two charged particles? Note that we're looking for an answer in units of centimeters.

(c)Finally, place the particle of charge ?4Q at the correct location so that the ?4Q charge experiences no net force because of the other two charged particles. In that situation, calculate the magnitude of the force that just one of the other charged particles exerts on the ?4Q charge.

Explain the phenomenon of induction that was studied in this activity (bringing a negatively charged plastic rod near an uncharged non-metal-coated styrofoam ball that is hanging freely and an uncharged metal-coated styrofoam ball that is hanging). For example, explain how a metal conductor such as a hanging ball of aluminum foil can be attarcted to a charged insulator even though the ball of foil has no net charge so that is is electrically neutral. Can two metal balls with no net charge attract each other? Explain. Can the process of induction cause a neutral conductor to be repelled from a charged insulator? Explain.

Thank you very much :)

Three vectors are given as A=<3.5, -5.3, 1.1> B=<4.5, 7.5, -7> C=<-3.9, 4.8, -6>

a) Determine the angle between A and B.

b) Determine the angle between A and C

c) Compute the dot product of B and C

d) Determine the size of the area associated with vectors B and C.

e) Determine the quantity (B (dot)(A(cross)C))

Two horizontal metal plates, each 10.0 cm square, are aligned 1.00 cm apart with one above the other. They are given equal-magnitude charges of opposite sign so that a uniform downward electric field of 1.96 103 N/C exists in the region between them. A particle of mass 2.00 10-16 kg and with a positive charge of 1.09 10-6 C leaves the center of the bottom negative plate with an initial speed of 1.04 105 m/s at an angle of 37.0° above the horizontal. (c) Where does it strike, relative to its starting point? (Enter the horizontal distance from the initial position.)

1 (a) Assume that the lights in your kitchen use 300 watts. How much energy and how much does it cost to leave the lights on 24 hours a day for a week if electricity is 8 cents/kilowatt hour?

(b) For a month (assume 30 days/month)?

(c) For a year?

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2 (a) How much energy and how much money do you use to run your window air conditioner rated at 1500 watts continuously for the month of July (assume 8¢/kWh)?

(b) If you assume that coal was used to produce the electricity for your air conditioner, how much coal was burned to produce the electricity used?

(c) How much CO2 was produced by the electricity used to run your air conditioner?

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3 (a) An average incandescent light bulb has a life expectancy of 1,000 hours. How much energy would a typical 60 watt bulb use in a lifetime, assuming it lasts for 1,000 hours?

(b) At 8¢/kWh, how much would it cost over its lifetime?

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4 (a) A compact fluorescent bulb uses 15 watts and has a life expectancy of 10,000 hours. How much energy and how much would it cost to use a compact fluorescent for 10,000 hours?

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5 (a) If your car gets 20 miles per gallon (MPG), and you drive an average of 10,000 miles each year, how many gallons of gas do you use a year?

(b) At $3.00 per gallon, how much will you spend on gasoline for the year?

(c) If the combustion of each gallon of gasoline produces 22 lbs of CO2, how much CO2 does your car produce each year?

(d) If you traded your car in & bought one that got 25 MPG, how much gasoline would you save in one year?

(e) How much money would you save?

(f) How much less CO2 would be emitted into the atmosphere from your improved car?

A damped oscillator has a frequency w' that is 10% less than its undamped frequency. a) By what factor is the amplitude of the oscillation decreased during each oscillation? b) By what factor is its energy reduced during each oscillation.