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katen-ka-za [31]

3 years ago

11

Humans have existed for about 106 years, whereas the universe is about 1010 years old. If the age of the universe is defined as

1 "universe day," where a universe day consists of "universe seconds" as a normal day consists of normal seconds, how many universe seconds have humans existed?

1 answer:

son4ous [18]3 years ago

8 0

Answer:

8.64 seconds

Explanation:

According to the question

$10^{10}\ years=1\ day$

$1\ year=\dfrac{1}{10^{10}}\ day$

Humans have lived for $10^6$ years

In one universe day

$10^6\ years=10^6\times \dfrac{1}{10^{10}}=10^{-4}\ day$

In seconds

$10^{-4}\times 24\times 60\times 60=8.64\ seconds$

In one universe day humans have lived for 8.64 seconds

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How much work is done? A Net Force of 9.0 N acts through a distance of 3.0 m in a time of 3.0 s. The answers are 3.0 J, 9.0 J, 2

Vadim26 [7]

If the force and the motion are along the same direction (like it is here) then work is force*distance. The time doesn't come into play until you want the power used. So here
W=9.0*3.0=27J

5 0

4 years ago

An ambulance is traveling north at 55.9 m/s, approaching a car that is also traveling north at 28.4 m/s. The ambulance driver he

wlad13 [49]

Answer:

915 Hz

Explanation:

The observed frequency from a sound source is given as

f₀ = f [(v + v₀)/(v+vₛ)]

where

f₀ = observed frequency of the sound by the observer = ?

f = actual frequency of the sound wave = 983 Hz

v = actual velocity of the sound waves = 343 m/s

vₛ = velocity of the source of the sound waves = 55.9 m/s

v₀ = velocity of the observer = 28.4 m/s

f₀ = 983 [(343+28.4)/(343+55.9)]

f₀ = 915.2 Hz = 915 Hz

6 0

3 years ago

A small object carrying a charge of -4.00 nC is acted upon by a downward force of 24.0 nN when placed at a certain point in an e

PIT_PIT [208]

Answer:

$E = -6 \ N/C$

Generally given that the electric field is negative it mean that its direction is opposite to that of the force

Explanation:

From the question we are told that

The charge on the small object is $Q = -4.00 \ nC = -4.00 *10^{-9} \ C$

The force is $F = 24 \ nN = 24 *10^{-9} \ N$

Generally the magnitude of the electric field is mathematically represented as

$E = \frac{F}{Q}$

=> $E = \frac{ 24 *10^{-9}} {-4 *10^{-9 }}$

=> $E = -6 \ N/C$

Generally given that the electric field is negative it mean that its direction is opposite to that of the force

6 0

3 years ago

The work function for a metal surface is 4.98 eV. What is the largest wavelength of light in nm that will produce photoelectrons

bulgar [2K]

Answer: $\lambda =248.99 nm$

Explanation:

Given

Work function $\left ( \phi \right )=4.98\approx 1.602\times 10^{-19}\times 4.98$

$h=6.626\times 10^{-34} J$

$c=2.998\times 10^8$

$\phi =\frac{hc}{\lambda }$

$\lambda =\frac{hc}{\phi }$

$\lambda =\frac{6.626\times 10^{-34}\times 2.998\times 10^8}{4.98\times 1.602\times 10^{-19}}$

$\lambda =248.99 nm$

3 0

3 years ago

It is claimed that if a lead bullet goes fast enough, it can melt completely when it comes to a halt suddenly, and all its kinet

Amiraneli [1.4K]

Answer:

354.72 m/s

Explanation:

$m$ = mass of lead bullet

$c$ = specific heat of lead = 128 J/(kg °C)

$L$ = Latent heat of fusion of lead = 24500 J/kg

$T_{i}$ = initial temperature = 27.4 °C

$T_{f}$ = final temperature = melting point of lead = 327.5 °C

$v$ = Speed of lead bullet

Using conservation of energy

Kinetic energy of bullet = Heat required for change of temperature + Heat of melting

$(0.5) m v^{2} = m c (T_{f} - T_{i}) + m L\\(0.5) v^{2} = c (T_{f} - T_{i}) + L\\(0.5) v^{2} = (128) (327.5 - 27.4) + 24500\\(0.5) v^{2} = 62912.8\\v = 354.72 ms^{-1}$

3 0

3 years ago