A 60 Watt light bulb runs for 120 seconds. How much energy does it use?

You need to know the height of a tower, but darkness obscures the ceiling. You note that a pendulum extending from the ceiling a

larisa86 [58]

Answer:

120 m

Explanation:

We can calculate the period of a pendulum using the following expression.

$T=2\pi \sqrt{\frac{L}{g} }$

where,

T is the period of the pendulum

L is the length of the pendulum (here it coincides with the height of the tower)

g is the gravity

$T=2\pi \sqrt{\frac{L}{g} }\\L=(\frac{T}{2\pi } )^{2} g=(\frac{22s}{2\pi} )^{2} .9.81m/s^{2} =120m$

6 0

3 years ago

An electron in a tv picture tube is accelerated through a potential difference of 10 kv before it hits the screen. What is the k

fomenos

Answer:

10,000 eV

Explanation:

Due to the law of conservation of energy, the kinetic energy of the electron at the end of its path is equal to its initial electric potential energy, given by:

$U=q\Delta V$

where

q is the electron charge

$\Delta V$ is the potential difference

Here we have:

$q=1 e$ is the electron's charged

$\Delta V=10 kV=10,000 V$ is the potential difference

Substituting into the formula, we have

$U=(1e)(10,000 V)=10,000 eV$

8 0

4 years ago

If a wave hits a smooth surface at an angle of incidence of 40 degrees, the angle of reflection is

navik [9.2K]

D. 80 degrees.


The part of the ear where sound wave compressions and rarefactions cause the eardrum to vibrate is the middle ear. The 8th nerve in the inner ear actually converts the mechanical energy to electrical energy for transmitting to the brain. A membrane called the tympanic membrane separates the middle ear from the outer ear. Whenever a sound reaches the ear, it creates a sound wave that creates vibration in the eardrum. The pressure when high pushes the membrane inwards while low pressure sound waves helps the eardrum to come outwards.

3 0

3 years ago

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Gravitational force between two objects depends on:

Ulleksa [173]

The strength of the gravitational force between two objects depends on two factors, mass and distance. the force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. thats what i got..

4 0

4 years ago

Read 2 more answers

A current of 0.86 a flows through a copper wire 0.47 mm in diameter when it is connected to a potential difference of 15 v. how

likoan [24]

To calculate the length of the wire, we use formulas,

$R = \frac{V}{I}$ (A)

$R= \rho \frac{l}{A}$ (B)

Here, R is the resistance of the wire, I is the current flows through wire and V is potential difference. A is cross sectional area of wire and $\rho$ is the density of copper wire and is value, $\rho = 1.7\times 10^{-8} \Omega m$ .

Given $I = 0.86 A,V=15 V and r = \frac{0.47 mm}{2} =2.35 \times 10^{-4} m, V= 15 V.$

Substituting the values of I and V in equation (A ) we get,

$R=\frac{15V}{0.86A} = 17.44 \Omega$

Now from equation (B),

$l=\frac{R A}{\rho }$

Therefore,

$l= \frac{17.44\times\pi \times r^2 }{1.7\times 10^{8} \Omega m} \\\\ l= \frac{17.44\times 3.14 \times(2.35\times10^{-4}m)^2 }{1.7\times 10^{-8} \Omega m} = 177.9 m$

Thus the length of the copper wire is 177.9 m.

8 0

3 years ago