Physics Answers

40. What is the velocity of the wave in a guitar string having a length of 0.65 m

and a mass of 3.5 g when subjected to a tension of 250 N?

41. While fishing, you notice that eight crests pass a given point in a time

interval of 10s. You approximate the distance between two crests to be 1.2

m. Calculate the

a) Speed of water waves and

b) Depth of water

42. On November 7, 1940, the Tacoma Narrows suspension bridge collapsed just

four months after it opened. Do research on causes why the bridge had set

in motion that led to its collapsed.

Given:

G = 6.67 x 10-11 N m2 kg-2

mass of the Earth = 6.0 x 1024 kg

radius of the Earth = 6.4 x 106 m

gravitational field strength close to the surface of the Earth is 9.8 N

kg-1 15

19. What is the gravitational potential energy of a 60 kg student on

the surface of the Earth? What then, is the minimum energy

that would be required to get this student completely out of the

Earth’s gravitational field?

20. You’re in the design of mission carrying humans to the surface

of the planet Mars, which has a radius of 3.38 x 106 m and a

mass of 6.24 x 1023 kg. The Earth weigh of the Mar’s lander is

39,200 N. Calculate its weight and the acceleration due to Mar’s

gravity at 6.0 x 106 m above the surface of Mars.

1. A flywheel, in the form of uniform disk, is 4.0 m in diameter and

weighs 637 N. What will be its angular acceleration if it is

activated upon by net torque of 225J?

2. When you switch your room fan from medium to high speed, the

blades accelerate at 1.2 radians per second squared for 1.5

seconds. If the initial angular speed of the fan blades is 3.0

radians per second, what is the final angular speed of the fan

blades in radians per second?

A particle of charge 4.25x10-9 C moves at 3.0x10* m/s at 60° up the x-y plane through a uniform magnetic field of 5.0x10-³T directed along the +z-axis. Find the magnetic force on the particle.

Two equal charges are separated 75cm apart in free air.

Calculate the quantity of either charge if the force between them is 0.17N.

What will be the quantity if the charges are situated in an insulating medium of dielectric constant= 10?

A metal is tested to have a charge of 697.6C. How many electrons are added to it to acquire the charge?

If two similarly charged metals are brought 1.5m apart in a medium of dielectric constant 2, calculate the force between them.

Is the force attractive or repulsive?

1. Every weekend, you and your family always find time to bood with each other. All of your family members are fully vaccinated, and they decided to have a two days vacation in Cebu City. You choose to ride a private helicopter towards your destination. You noticed that the helicopter has two sets of lifting blades, they rotate in opposite directions (and there will be no sail propeller). Explain why it is best to have the blades rotates in opposites directions.

2. When you start the enige of your car with the transmission in restral, you notice that the car rocks in the opposite sense of the engine's rotation. Explain in terms of conservation of angular momentum. Is the angular momentum of the car conserved for long (for more than a few seconds)?

3. In a playground, there is a small merry-go-round. Suppose a child walks from the outer edge of a rotating merry-go-round inside, does the angular velocity of the merry-go-round increase, decrease or remain the same? Explain your answer.

A transverse wave on a taut string is modeled with the wave function

y(x, t) = Asin(kx-wt)

(0.25m) sin(6.48m-'x- 1.47s1 t)

Find the: (a) amplitude, (b) wavelength, (c) period, (d) direction of

: )

propagation and (e) speed of the wave.

If the entire earth, except for a feather, just winked out of existence, would the feather follow the same orbit that the earth was in?

Determine the force required to be generated by a flying saucer of mass 1.94 x 10¹⁶ µg to rise from ground level with an acceleration of 5.18 x 10⁸ Km/h upward. (b) Find the work done by this force if the saucer is elevated 196 hm from the ground.