Classical Mechanics

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Period of a pendulum - amplitude

When the amplitude of a pendulum decreases to half its initial value. Will the period have doubled, halved or stayed the same?

Force and Tension

A tightly stretched "high wire" is 42.8 m long. It sags 3.5 m when a 63.8 kg tightrope walker stands at its center. What is the tension in the wire?

A solenoid 12 cm long has a total of 10,000 turns of wire uniformly distributed along its length. It carries a current of 0.833 A and is filled with a ferromagnetic material with a permeability 700 times the permeability of free space What is the magnitude of B at the center?

Tension in a sphere

A spherical shaped hollow steel shell with a radius of 2.5 m containing some instruments is lowerd by a cable into a lake the shell with its contents weighs 7.5*10^5N on the deck of the ship wich is being lowered. What is the tension in the cable when the sphere is completly immersed in the water?

Kinetic friction

If an object slides directly down an inclined place, at a constant velocity of 6 m/s, how large is the coefficient of kinetic friction if the plane make an angle of 25 degrees with the horizontal?

Do length contraction and time dilation occur at ordinary speeds

Do length contraction and time dilation occur at ordinary speeds (120 km/hr)?

Waves on a string: By what factor should the tension in this string be changed to produce waves with a speed of 32 m/s?

Waves on a particular string travels with a speed of 16 m/s. By what factor should the tension in this string be changed to produce waves with a speed of 32 m/s?

Finding Wavelength and Amplitude

A wave travels along a stretched rope. The vertical distance from crest to trough for this wave is 17 cm and the horizontal distance from crest to trough is 23 cm. What is: (a) the wavelength and (b) the amplitude of this wave?

Solve: Distance and Time

Hi, I need some assistance with the following questions: Question: At the average rate of 15 m/s^2. How much time does it take for the complete increase in speed? a. 0.25 s b. 4.0 s c. 0.0577 s d. 17.3 s e. 8.0 s Question: A car traveling 20 m/s is able to stop in a distance d. Assuming the same braking force, what

A 200 g object is moving in a circle of radius 4.0 m a

A 200 g object is moving in a circle of radius 4.0 m a uniform speed of 6.0 m/s. the net force acting on the object is: a. 3.6 N towards the center of the circle b. 3.6 N tangential to the circle c 1.8 towards the center of the circle d. 1.8 N away from the center 0f the circle

Two objects have the same kinetic energy. if the

Two objects have the same kinetic energy. if the object is moving 3 times faster than second object, what is the second object's mass in comparison to the first object's mass? a. 3 times larger b. it is the same c. 9 times larger d. can not determine

A cylindrical specimen of steel

A cylindrical specimen of steel of cross sectional area 5 cm^2 is subjected to a tensile force of 800 N. the stress in material is a. 8.0 * 10^3 N/m^2 b 4.0 * 10^3 N/m^2 c. 1.6 * 10^6 N/m^2 d. 3.2 *10^6 N/m^2

A safe

A safe with a mass of 150kg is at rest on the floor. what is the minimum horizontal force needed to move the safe if the coefficent of static friction between the safe and the floor is 0.3? a.441n b. 51n c.501n d.41n

Simple Harmonic Motion.

I have to find the mass of an object. The problem is that my result is a negative one. The problem is as follows: A teacher demonstrates a harmonic motion with an object of mass m0, hung on a wire with constant k. A mass of 1,25g is added to the object, which results in a loss of 2.5% of the original frequency. What is the

Multiple choice question on elongation of wire

The weight that will cause a wire of diameter d to stretch a given distance, for a fixed length of wire, is a. proportional to d^2 b. independant of d c. proportional to d d. independant of what the lengthof wire is

Pulley

What is a pulley? where is it used?

A spherical-shaped hollow

A spherical-shaped hollow steel shell, with a radius of 2.5m, containing some instruments, is lowered by a cable into a lake. The shell with its contents weighs 7.2 * 10^5 N on the deck of the ship from which it is being lowered. What is the tension in the cable when the sphere is completely immersed in water? a. 1.8 kg b. 2

Elastic Modulus

A copper wire has a length of 5.0 m and a diameter of 3.0mm. Under what load will it's length increase by 0.3 mm?

Fluids: Pressure and Pascal's Principle

A 75 kg athlete does a single handstand. If the area of the hand is in contact with the floor is 125 cm^2, what pressure is exerted on the floor?

Force and Shear Moduli

Two metal plates are held together by two steel rivets, each of diameter 0.20 cm and length 1.0 cm. How much force must be applied parallel to the plates to shear off both rivets? The shear modulus of steel is 8.2 x 10^10.

Question about Solids and Elastic Moduli

A copper wire has a length of 5.0m and a diameter of 3.0 mm. Under what load will its length increase by 0.3 mm. (If you need Young's Modulus (Y) for copper it is 11 x 10^10N/m^2.)

Solving an Elasticity Problem

A phone line 2.0 m in diameter and 0.5 km long is stretched 0.5 m by a force of 4000 N. Determine: 1. the stress on the wire 2. the strain on the wire 3.Young's modulus for the cable material.

Speed of a Rolling Hoop

A hoop of radius 0.5 m and a mass of 0.2kg is released from rest and allowed to roll down an inclined plane. How fast is it moving after being dropped from a vertical distance of 3m? a. 5.4 m/s b. 3.8 m/s c. 7.7 m/s d. 2.2 m/s

How Long Would It Take a Roofer to Lift a Load?

A roofer lifts supplies to a height of 20m with a hand-operated wench. How long would it take him to lift a 200-kg load, if the wench has an efficency of 90%, and the rate at which the wench can do work is .8hp?

Determine the Air Mass flow Rate Through the Core of a Jet Engine

The by Pass Ratio of the JT9D-3A engine is 5.17:1. If the air mass flow through the fan is 577 kg/s, determine the air mass flow through the core.

Linear Momentum and Collisions

A 16 g rifle bullet traveling 150 m/s buries itself in a 4.0 kg pendulum hanging on a 3.3 m long string, which makes the pendulum swing upward in an arc. Determine the horizontal component of the pendulum's displacement.

Physics: Springs and Compression

1. A spring is compressed 10 cm by pushing a body against it. When released the spring pushes the body towards another identical spring. The body must slide over a rough floor in order to reach the second spring. When it makes contact the body compresses the opposite spring by 8 cm. Once again the body is forced back over the ro

Linear Momentum and a Jet Catapult on an Aircraft

A jet catapult on an aircraft carrier accelerates a 20000 kg plane uniformly from rest over a distance of 50.0 meters (for 2 seconds) to launch speed of 50 m/sec. What is the magnitude of the net force on the plane?

Determining if a Copper Bowl Will Float

A hemispherical copper bowl with an outer diameter of 10cm and wall thickness 1mm is placed in a large bath of water. Will it float? (See attachment for diagram.) If it does float, how far will the base of the bowl sink beneath the water surface? Note: Density of copper 8960 kgm-3 Finally, perform a 'back of the envelo

Finding the Center of Mass of a Rod

A 3.0 kg rod of length 5.0 m has at opposite ends point masses of 4.0 kg and 6.0 kg(a) Will the center of mass of this system be (1) nearer to the 4.0 kg mass, (2) nearer to the 6.0 kg mass, or (3) at the center of the rod? Why? (b) Where is the center of mass of the system?

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