# Posts by opp

Total # Posts: 37

**physics**

why do you find the same wavelengths and colors on each side of the central maxima?

*November 29, 2012*

**physics**

Unpolarized light is incident on four polarizing sheets with their transmission axes oriented as shown in the figure, in which θ1 = 27.0° and θ2 = 50.0°. What percentage of the initial light intensity is transmitted through this set of polarizers?

*November 5, 2012*

**phys**

Two concentric circular wire loops in the same plane each carry a current. The larger loop has a current of 8.62 A circulating clockwise and has a radius of 6.09 cm. The smaller loop has a radius of 4.42 cm. What is the current in the smaller loop if the total magnetic field ...

*October 4, 2012*

**physics**

Consider the circuit in the diagram. Let R1 = 51.0 Ω, R2 = 38.0 Ω, R3 = 74.0 Ω, R4 = 16.0 Ω, and V = 84 V. (b) What current flows from the battery? (c) What is the potential difference between points A and B? (d) What current flows through each branch ...

*September 25, 2012*

**physics**

A horizontal beam of electrons initially moving at 4.3 107 m/s is deflected vertically by the vertical electric field between oppositely charged parallel plates as shown in the diagram. The magnitude of the field is 1.90 104 N/C. What is the vertical deflection d of the ...

*September 6, 2012*

**phys**

A town is planning on using the water flowing through a river at a rate of 4.9 106 kg/s to carry away the heat from a new power plant. Environmental studies indicate that the temperature of the river should only increase by 0.50° C. The maximum design efficiency for this ...

*April 30, 2012*

**phys**

A reversible engine with an efficiency of 32.0% has TC = 304.0 K. (a) What is TH? (b) How much heat is exhausted for every 0.138 kJ of work done?

*April 30, 2012*

**phys**

thank you...what I originally did was use the wrong specific heat for iron.

*April 26, 2012*

**phys**

A 10.9-g iron bullet with a speed of 4.00 102 m/s and a temperature of 20.0° C is stopped in a 0.400-kg block of wood, also at 20.0° C. (a) At first all of the bullet's kinetic energy goes into the internal energy of the bullet. Calculate the temperature increase ...

*April 26, 2012*

**phys**

A 30.0-g lead bullet leaves a rifle at a temperature of 89.0° C and hits a steel plate. If the bullet melts, what is the minimum speed it must have?

*April 26, 2012*

**phys**

A 0.600-kg aluminum teakettle contains 4.00 kg of water at 26.0° C. How much heat is required to raise the temperature of the water (and kettle) to 100.0° C?

*April 25, 2012*

**phys**

What is the total translational kinetic energy of the gas molecules of 0.470 mol of air at atmospheric pressure that occupies a volume of 1.00 L (0.00100 m3)?

*April 25, 2012*

**phys**

A cylinder in a car engine takes Vi = 4.50 10-2 m3 of air into the chamber at 30° C and at atmospheric pressure. The piston then compresses the air to 0.112 times of the original volume (0.112 Vi) and to 24.0 times the original pressure (24.0 Pi). What is the new ...

*April 25, 2012*

**chem/phys**

Calculate the number of H2O molecules in a human body of mass 66.5 kg. Assume that, on average, water makes up 62% of the mass of a human body. (Use 1.0 u for the atomic mass of hydrogen, and 16.0 u for the atomic mass of oxygen.) 1

*April 25, 2012*

**physics**

A sound wave with intensity 37 mW/m2 interferes constructively with a sound wave that has an intensity of 18 mW/m2. What is the intensity of the superposition of the two?

*April 10, 2012*

**physics**

An experimental flywheel, used to store energy and replace an automobile engine, is a solid disk of mass 202.0 kg and radius 0.35 m. (a) What is its rotational inertia? (b) When driving at 22.4 m/s (50 mph), the fully energized flywheel is rotating at an angular speed of 3160 ...

*March 22, 2012*

**physics**

A modern sculpture has a large horizontal spring, with a spring constant of 277 N/m, that is attached to a 58.0-kg piece of uniform metal at its end and holds the metal at an angle of θ = 48.0° above the horizontal direction. The other end of the metal is wedged into ...

*March 22, 2012*

**physics14**

A uniform disk with a mass of 900 g and radius 17.0 cm is rotating on frictionless bearings with an rotational speed of 18.0 Hz when Jill drops a 180-g clod of clay on a point 8.70 cm from the center of the disk, where it sticks. What is the new rotational speed of the disk?

*March 22, 2012*

**p**

A weightless rod, with length d = 5.5 m, supports three weights with masses m1 = 3 kg, m2 = 14 kg, and m3 = 4 kg as shown. Where is its center of gravity?

*March 21, 2012*

**phy**

How much work is done by the motor in a CD player to make a CD spin, starting from rest? The CD has a diameter of 12.8 cm and a mass of 15.7 g. The laser scans at a constant tangential velocity of 1.23 m/s. Assume that the music is first detected at a radius of 19.1 mm from ...

*March 21, 2012*

**phy3**

A 0.01-kg baseball traveling in a horizontal direction with a speed of 11 m/s hits a bat and is popped straight up with a speed of 15 m/s. (a) What is the change in momentum (magnitude and direction) of the baseball?

*March 17, 2012*

**phys3**

A projectile of mass 2.0 kg approaches a stationary target body at 4.9 m/s. The projectile is deflected through an angle of 59.8° and its speed after the collision is 2.8 m/s. What is the magnitude of the momentum of the target body after the collision?

*March 17, 2012*

**phys2**

A 60-kg astronaut is in space, far from any objects that would exert a significant gravitational force on him. He would like to move toward his spaceship, but his jet pack is not functioning. He throws a 720-g socket wrench with a velocity of 5 m/s in a direction away from the...

*March 17, 2012*

**p3**

A block of wood of mass 0.86 kg is initially at rest. A bullet of mass 0.048 kg traveling at 102.3 m/s strikes the block and becomes embedded in it. With what speed do the block of wood and the bullet move just after the collision?

*March 14, 2012*

**p**

A uranium nucleus (mass 238 u), initially at rest, undergoes radioactive decay. After an alpha particle (mass 4.0 u) is emitted, the remaining nucleus is thorium (mass 234 u). If the alpha particle is moving at 0.052 the speed of light, what is the recoil speed of the thorium ...

*March 14, 2012*

**p**

What is the momentum of an automobile (weight = 9600 N) when it is moving at 38 m/s to the south?

*March 14, 2012*

**phys4**

A hang glider moving at speed 9.0 m/s dives to an altitude 4.2 m lower. Ignoring drag, how fast is it then moving?

*February 26, 2012*

**phys3**

A motorist driving a 1100-kg car on level ground accelerates from 20.0 m/s to 30.0 m/s in a time of 5.6 s. Neglecting friction and air resistance, determine the average mechanical power in watts the engine must supply during this time interval.

*February 26, 2012*

**phys2**

A 2.9-kg block is released from rest and allowed to slide down a frictionless surface and into a spring. The far end of the spring is attached to a wall, as shown. The initial height of the block is 0.34 m above the lowest part of the slide and the spring constant is 347 N/m...

*February 26, 2012*

**phys1**

A 528 kg automobile is moving at 20.4 m/s at a height of 5.0 m above the bottom of a hill when it runs out of gasoline. The car coasts down the hill and then continues coasting up the other side until it comes to rest. Ignoring frictional forces and air resistance, what is the...

*February 26, 2012*

**physorbit**

A spacecraft is in orbit around a planet. The radius of the orbit is 3.2 times the radius of the planet (which is R = 71490 km). The gravitational field at the surface of the planet is 24 N/kg. What is the period of the spacecraft's orbit?

*February 21, 2012*

**physAH!**

A car that is initially at rest moves along a circular path with a constant tangential acceleration component of 2.07 m/s2. The circular path has a radius of 42.4 m. The initial position of the car is at the far west location on the circle and the initial velocity is to the ...

*February 20, 2012*

**phys6**

A cyclist starts from rest and pedals so that the wheels make 8.1 revolutions in the first 5.4 s. What is the angular acceleration of the wheels (assumed constant)?

*February 20, 2012*

**phys5**

A child pushes a merry go-round from rest to a final angular speed of 0.44 rev/s with constant angular acceleration. In doing so, the child pushes the merry-go-round 1.8 revolutions. What is the angular acceleration of the merry go-round?

*February 20, 2012*

**phys4**

A 31.5-kg child swings on a rope with a length of 6.26 m that is hanging from a tree. At the bottom of the swing, the child is moving at a speed of 4.2 m/s. What is the tension in the rope?

*February 20, 2012*

**phys3**

A biologist is studying growth in space. He wants to simulate Earth's gravitational field, so he positions the plants on a rotating platform in the spaceship. The distance of each plant from the central axis of rotation is r = 0.11 m. What angular speed is required?

*February 20, 2012*

**phys2**

Grace is playing with her dolls and decides to give them a ride on a merry-go-round. She places one of them on an old record player turntable and sets the angular speed at 45.0 rpm. (a) What is their angular speed in rad/s? 1 Correct: Your answer is correct. rad/s (b) If the ...

*February 20, 2012*

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