A lens is made with focal length -40 cm using a material with index of refraction 1.50. A second lens is made with the same geometry as the first but using a higher index material, the index being 2.00
To lift the 5000-N block, the man finds that he must pull 10 m of rope through his hands for every 1 m the block rises. Neglecting the weights of the pulleys and friction, how hard must the man pull on the rope to raise the block?
Two point charges, one q and the other –q, form a dipole separated by a distance d. A third charge Q is placed midway between these two charges. If the distance between q and –q is then doubled with the Q staying midway between the other two, what happens to the force on Q?
Equilibrium: A 40-kg uniform ladder that is 5.0 m long is placed against a smooth wall at a height of h = 4.0 m, as shown in the figure. The base of the ladder rests on a rough horizontal surface whose coefficient of static friction with the ladder is 0.40. An 80-kg bucket is suspended from the top rung of the ladder, just at the wall. What is the magnitude of the force that the ladder exerts on the wall?<img src="https://sciemce.com/files/4/ppg__cp1pbb0313192044__f104g1q24g1.jpg" alt="" style="vertical-align: 0.0px;" height="317" width="175" />
An electron is accelerated from rest through a potential difference of 3750 V. It enters a region where the magnetic field is 4.0 mT perpendicular to the velocity of the electron. Calculate the radius of the path this electron will follow
A star like the sun has a luminosity of <img src="https://sciemce.com/files/4/8e613f2e61a58c7107.png" class="w-image" /> How much mass must be turned into energy each second to produce this power?
An ideal step-down transformer has 200 primary turns and 50 secondary turns. If 440 volts (rms) is placed across the primary, what is the current in the secondary when the load resistance is 7.00 ohms?
A modern version of Joule's experiment has you turn a crank attached to an 85.0 g aluminum cylinder. A belt exerts a frictional torque on the cylinder of 1.50 Nm. The specific heat of aluminum is 900 J/(kg•K)
The horizontal surface on which the block slides is frictionless. The speed of the block before it touches the spring is 6.0 m/s. How fast is the block moving at the instant the spring has been compressed 15 cm? k = 2.0 kN/m<img src="https://sciemce.com/files/2/ppg__cognero__Chapter_8_Conservation_of_Energy.__media__9eff0359-2d42-4cf9-b672-2fcae5fd643e.PNG" style="vertical-align: 0px;" width="257px" height="101px" />
Conversion of Units: The radius of the earth is 3963 mi. Which one of the following numbers is closest to the surface area of the earth? (1.0 mi = 1609 m)
A series of 3 uncharged concentric spherical conducting shells surround a small central charge q. The potential at a point outside the third shell, at distance r from the center, and relative to V = 0 at ∞, is
Which of the following best describes the image of a convex mirror when the object's distance from the mirror is less than the absolute value of the focal point distance?
Buoyancy: A rectangular box of negligible mass measures 5.0 m long, 1.0 m wide, and 0.50 m high. How many kilograms of mass can be loaded onto the box before it sinks in a lake having water of density 1000 kg/m3?
A 120 N traffic light is located at the midpoint of a cable between two poles. The cable makes and angle of 30<img src="https://sciemce.com/files/4/cf2467007209c52937.png" class="w-image" />to the horizontal at each pole. What is the tension in the cable?
An RC circuit consists of 2.0 MΩ in series with a capacitor. When connected to a battery, the capacitor becomes 25% charged in 1.5 seconds. What is the capacitance value?
Consider two identical and symmetrical wave pulses on a string. Suppose the first pulse reaches the fixed end of the string and is reflected back and then meets the second pulse. When the two pulses overlap exactly, the superposition principle predicts that the amplitude of the resultant pulses, at that moment, will be what factor times the amplitude of one of the original pulses?
The figure shows the graph of <img src="https://sciemce.com/files/4/c0106240c2445258135.png" class="w-image" />versus time for an object moving along the x-axis. Solve graphically for the distance traveled from t = 9.0 s to t = 13.0 s.
Uniform Circular Motion: A particularly scary roller coaster contains a loop-the-loop in which the car and rider are completely upside down. If the radius of the loop is 13.2 m, with what minimum speed must the car traverse the loop so that the rider does not fall out while upside down at the top? Assume the rider is not strapped to the car.
A block and a beaker of water are placed side-by-side on a scale (case A). The block is then placed into the beaker of water, where it floats (case B). How do the two scale readings compare?
In looking at yourself in a steamy mirror you wipe just enough moisture away to barely see a full view of your face. If you move back from the mirror you'll see
Energy and Mass: An electron-volt is the energy gained by an electron if it is accelerated through a potential difference of one volt. What is the equivalent to an electron-volt in kilograms? (c = 3.00 × 108 m/s, e = 1.60 × 10-19 C)
The velocity of an airplane with respect to the ground is <img src="https://sciemce.com/files/4/3b04d67bf8e9be0729.png" class="w-image" />m/s at an angle of 30.0 degrees NORTH of EAST. The velocity of the airplane with respect to the air is <img src="https://sciemce.com/files/4/fe299fd2732c0b0c30.png" class="w-image" />m/s at an angle of 60.0 degrees NORTH of EAST. What is the velocity of the air with respect to the ground?
General Questions: A person who normally weighs 700 N is riding in an elevator that is moving upward but slowing down at a steady rate. If this person is standing on a bathroom scale inside the elevator, what would the scale read?
A cylinder contains 23 moles of an ideal gas at a temperature of 300 K. The gas is compressed at constant pressure until the final volume equals 0.43 times the initial volume
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