Physics Answers

In a charming 19th-century hotel, an old-style elevator is connected to a counterweight by a cable that passes over a rotating disk 2.8m in diameter. The elevator is raised and lowered by turning the disk, and the cable does not slip on the rim of the disk but turns with it. At how many rpm (revolutions per minute) must the disk turn to raise the elevator at 37 cm/s?

The potential difference across the terminals of a battery with an internal resistance of 0.5 Ohms in a closed and open circuit are 8.5 V and 12.0V, respectively. How much current is flowing when the circuit is closed?

A 1 kilogram object is located at a distance of 6.4x10 to the 6th m from the center of a larger object whose mass is 6 by 10 to the 24th kg. What is the force acting between the objects?

You're standing on the edge of a vertical cliff of height H. The ground below is horizontal. You throw a baseball with speed v in horizontal forward direction. The ball hits the ground below.

Next, your friend throws a second (identical) baseball with the same speed v in forward direction but under an angle π/4 above the horizontal.

The acceleration of gravity is g (pointing downward) and air friction can be ignored.

Derive an expression of the speed v both baseballs should have to touch te ground at exactly the same spot. Express v in the given quantities and constants.

1. Determine thedisplacement of a periodic motion given that the time it takes to complete one cycle is 1 second and the amplitude is 1 meter (y=-3.071790 x 10-⁷ m)

2. What is the angular frequency of an oscillating device at a period of 150 ms? (w=2400°/sec or 41.8879 rad/sec)

3. A pendulum is observed to complete 20 full cycles in 58 seconds. Determine the frequency (f = 0.34 cycle/sec)

4. Determine the frequencies of the following periods

a. 30 seconds

b. 3 seconds

c. 30 ms

d. 3000 seconds

A 5-m rope is tied to a tree limb and used as a swing. Tarzan holds the rope in a horizontal orientation. Assuming that the frictional force is zero and there is no air resistance, determine the speed of Tarzan at the lowest point on the circular arc of the swing.

a lump of steel of mass 8 kg at 1000 k is dropped in 80 kg of oil at 300 k. calculate the entropy change of steel the oil and the universe. take specific heats of steel and oil as 0.5 kj/kg K and 3.5 Kj /kg K respectively

A stone is thrown into the air at a 15 m/s at an angle of 30 degree.

a. What is the height reached of the stone?

b. What is the time taken by the stone in the whole travel?

C. What is the ranged reached by the stone?

d. A ball is projected with initial velocity of 18 m/s at an angle of 25 degree. What is the time of flight of the ball?

e.What is the horizontal displacement of the object thrown into the air at a velocity of 30 m/s with an angle of 28 degree?

A 1.0 kg block of steel is heated in an oven to a temperature of 200 °C. It is then dropped into a tank containing 100 kg of water.                                                                                                                     

The experiment is then repeated using a 1.0 kg block of aluminum.

Which metal block will cause a bigger rise in the temperature of the water? Explain your answer.

You have measure the length of a rope as 15.46 m, using a meter ruler. Find the present error associated with the measurement.