8. Determine the desired quantity in each of the following collisions: (a) A student of mass 60kg sits on a rolling chair (assume no friction with the ground). He pulls out a fire extinguisher and fires 2kg of material at a velocity of 8m/s. How fast is he moving after this process? (b) A 90kg astronaut is traveling through space at a rate of 2m/s. He is holding a 5kg mass as he travels. How fast would he have to throw this mass in order to come to rest? (c) A box of mass 20kg slides across an icy floor at a rate of 5m/s. In order to stop it, we slide smaller boxes of mass of 0.8kg towards it at a rate of 1m/s. How many boxes must collide with (and stick to) it before it comes to a stop? (d) A football player with mass 70kg runs towards another at a rate of 4m/s. Realizing he’s about to get walloped, the second player runs towards the first at a rate of 2m/s. If the second player has a mass of only 50kg, what is the velocity of the pair after the collision? (e) Three billiard balls travel along a table. The first is moving rightwards with a speed of 2m/s, the second is moving leftwards with a speed of 2m/s, and the middle one lies halfway between the first two. What is the velocity of the ball in the middle after the collision?

(f) Alice, with a mass of 60kg, jumps upwards off the Earth. At the moment of her jump, how fast does she move the Earth in the opposite direction? (The mass of the earth is about 5.972 · 1024kg)

The power supplied by a torque, ?, to rotate an object at angular frequency, ?, is P = ??. A common car engine produces ? = 3000Nm at ? = 3000 RPM (rotations per minute). Suppose you want to create an electric car that runs on a battery and electric motor. Typically, electric car motors utilize a current of 100A and have a cross sectional area of 0.5m². Suppose also that the number of wire turns in the coil of the motor is N = 100.

Q1: How strong of a magnetic field is required to produce the same torque as a regular car engine?

When the motor is connected in series with the battery that powers it, we can treat it like a generic circuit element with effective resistance R that causes a voltage drop V = IR. By setting the electrical power consumed by the motor equal to the mechanical power used to push the car, P = ??, the effective resistance of the motor can be determined.

Q2: What is the effective resistance of the motor?

Q3: Determine the voltage of the battery?

Please show all work, I will rate high.

Why does a frisbee behave differently when thrown upside down?

A textbook of mass 2.00kg rests on a frictionless, horizontal surface. A cord attached to the book passes over a pulley whose diameter is 0.100m , to a hanging book with mass 2.98kg . The system is released from rest, and the books are observed to move a distance 1.15m over a time interval of 0.850s

IP A charge of 19.0 μC is held fixed at the origin.

Part A-

If a -5.50 μC charge with a mass of 3.60 g is released from rest at the position (0.925 mm, 1.17 mm), what is its speed when it is halfway to the origin?

Part B-

Suppose the -5.50 μCμC charge is released from rest at the point x = 1/2(0.925mm) and y = 1/2(1.17mm). When it is halfway to the origin, is its speed greater than, less than, or equal to the speed found in part A?

Part C-

Explain.

Essay answers are limited to about 500 words (3800 characters maximum, including spaces).

3800 Character(s) remaining

Part D-

Find the speed of the charge for the situation described in part B.

A rocket is projected upward from the earth's surface (r = R_E) with an initial speed v₀ that carries it to a distance r = 1.5 R_Efrom the center of the earth. What is the launch speed v₀? Assume that air friction can be ignored.

Suppose that each vehicle is initially moving at 7.0 m/s and that they undergo a perfectly inelastic head on collision. Each driver has a mass of 80.0 kg. Including the drivers, the total vehicle masses are 800 kg for the car and 4000 kg for the truck.

(a) if the collision time is 0.150 s, what average forces does the seatbelt exert on the truck driver? N

(b)What average force does the seatbelt exert on the car driver? N

Consider 3 long parallel wires arranged such that they form an equilateral triangle in a plane perpendicular to them. The upper wires carry l 185A and 13SA in the same direction while the lower wire carries lg 370A in opposite direction. Calculate the intensity (magnitude and direction) of the magnetic field at the center of the triangle. For direction specify an angle with respect to any line you want. 1.3

1. A large open tank contains fresh water of constant density (p = 1000 kg/m3).

a) Construct an algebraic expression for the absolute pressure (P) at a specific depth below the surface of the water (y) in terms of gravitational acceleration (g), the depth of water (y), and the density of water (ρ).

A 12.2??F capacitor is connected through a 0.885?M? resistor to a constant potential difference of 60.0 V.

Part A. Compute the charge on the capacitor at the following times after the connections are made: 0, 5.0

s, 10.0 s, 20.0 s, and 100.0 s.

Part B. Compute the charging currents at the same instants.

Answer the following short questions.

a. A rectangular block has a resistivity of ? and resistance of ?. If we scale it up in size by a factor of 2 in every direction, what is the new resistivity and resistance as a function of ? and ??

b. Small aircraft often use 24-V electrical systems rather than the 12-V systems used in automobiles, even though the electrical power requirements are roughly the same. This is because a 24-V system uses thinner wires and therefore weighs less. Explain this reasoning.

c. Show why the internal resistance of a source can be determined by dividing the open-circuit voltage by the short-circuit current.

d. Assuming each source has a small internal resistance, which circuit(s) would light up the light bulb? Which circuit(s) do you think would be likely to cause damage to the ammeter or voltmeter?

2. You have a battery, a voltmeter, and an ammeter, and you are asked to find the resistance perunit-length ?′ of a long spool of wire. You connect the voltmeter to the battery and it reads 3.2 V. You connect the battery to 20 m of the wire with the ammeter in series and it reads 9.6 A. You then connect a 50 m length of wire and the ammeter now reads 4.1 A.

a. What is the resistance per-unit-length of the wire and internal resistance of the battery?

b. If the wire is made from copper, with a resistivity of ? = 1.7×10−8 Ω⋅m, what is its diameter? c. What is the percentage of power dissipated within the internal resistance of the battery relative to the total power dissipated? Is this percentage larger, smaller, or the same as for the 50 m wire? 3. Consider the following circuit containing two sources, each with an internal resistance of 5 , and two load resistors, being 40  and 100 . a. How much current flows through this circuit and in what direction does it flow? b. What is the potential at a relative to ground? What is the potential at b relative to ground?

c. Where in the circuit is the potential the highest? Where is it the lowest?

d. Calculate the total power dissipated in both load resistors. 2 e. If the 100 Ω resistor is replaced by a short circuit, is the total power absorbed by the 40 Ω resistor greater than, equal to, or less than the total power initially absorbed by both resistors? f. How much power is supplied by each source? (Include the effect of the internal resistances.)

4. The average bulk resistivity inside the human body is about 5 Ω.m. The surface resistance of the skin varies considerably, from around 100,000 Ω for dry skin to 1000 Ω for wet skin. If the skin is broken and soaked in salt water, the skin resistance will even approach zero. Furthermore, the skin resistance can break down when voltages are high (above 500 V) or when voltages are changing (like under alternating current conditions). You can model the conducting path between the hands as three resistors in series. The first and third resistors represent the skin resistance while the second resistor represents the internal resistance of the body and can be modeled as a cylinder of diameter 10 cm and length 1.6 m.

a. Calculate the resistance between the hands for dry skin, wet skin, and broken soaked skin.

b. What potential difference would be needed for a lethal shock current of 100 mA in each of the three cases in part a (ignoring breakdown)?

c. Considering the chart below (taken from C. F. Dalziel, “Deleterious effects of electric shock,” 1961), how bad would a worst-case shock be from a 12 V DC car battery, your 50 V DC home phone line, and a 120 V 60 Hz wall outlet (i.e. with broken soaked skin)? Warning, don’t test any of these situations out at home! Despite your findings, there have been cases where people have died of an electric shock from a car battery. DC 60 Hz AC 10 kHz AC Effect Men Women Men Women Men Women Slight sensation on hand 1 mA 0.6 mA 0.4 mA 0.3 mA 7 mA 5 mA Perception threshold, median 5.2 mA 3.5 mA 1.1 mA 0.7 mA 12 mA 8 mA Shock, not painful and muscular control not lost 9 mA 6 mA 1.8 mA 1.2 mA 17 mA 11 mA Painful shock, muscular control lost by 0.5% 62 mA 41 mA 9 mA 6 mA 55 mA 37 mA Painful shock, let-go threshold, median 76 mA 51 mA 16 mA 10.5 mA 75 mA 50 mA Painful and severe shock, breathing difficult, muscular control lost by 99.5% 90 mA 60 mA 23 mA 15 mA 94 mA 63 mA Possible ventricular fibrillation 500 mA 500 mA 100 mA 100 mA n/a n/a

Question 1:

A near-sighted person might correct his vision by wearing diverging lenses with focal length f = -50cm . When wearing his glasses, he looks not at actual objects but at the virtual images of those objects formed by his glasses. Suppose he looks at a 12cm -long pencil held vertically 2.0m from his glasses. Use ray tracing to determine the location of the image. Answer is in meters.

Question 2:

A 1.0-cm-tall object is 60 cm in front of a diverging lens that has a -30 cm focal length.

a) Calculate the image position in cm.

b) Calculate the image height in cm.

Show work please! Thank you!!

Research and explain in more detail than given in the lecture pages how a Molecular switch works and what the prospects are for building a molecular computer that makes use of these switches.

It's possible to estimate the percentage of fat in the body by measuring the resistance of the upper leg rather than the upper arm; the calculation is similar. A person's leg meas-ures 40cm between the knee and the hip, with an average leg diameter (ignoring bone and other poorly conducting tissue) of 12cm . A potential difference of 0.79V causes a current of 1.6mA .

What are the fractions of muscle and fat in the leg?

Please show full work, and explantion, and units for full credit.

A car of mass 1110 kg enters a banked turn with a banking angle of 11.1° and a radius of 300 m at a speed of 30.0 m/s. The coefficient of static friction between the car’s wheels and the pavement is 0.0881. The turn covers a total of 1 45°.

(a) If the car experiences a drag force that of D=kv where k=32.0kg/s, how much thrust must the car provide to maintain constant velocity in the turn?

(b) If the engine of the car suddenly cuts out at 2.10 s after entering the curve, and the only tangential force acting on the car is the drag force, how fast will the car be traveling by the time it exits the curve?

(c) Will the car begin to slip before it exits the curve in this case above where the engine fails after 2.10 s?