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3 years ago

A laser pointer used in a lecture hall emits light at 650 nm what is the frequency

1 answer:

7 0

The formula for frequency is speed of light divided by wavelength. 650 nm represents the wavelength and 3x10^8 m/s is the speed of light. If you convert 650nm to meters you get 6.5x10^-7 m so you can divide using the formula above, giving you 4.6x10^14 1/s or Hz, the unit of frequency in Physics.

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Which two pieces of evidence most directky support the idea that all matter in the universe began as a sibgke point of energy.

Aleks04 [339]

Answer:

YOUR ANSWER IS GIVEN BELOW:

Explanation:

The abundance of helium in the universe and the redshift of light from the galaxies.

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2 years ago

A motorist travels at 270 km in p hours at a certain average speed. an expression for the distance that this motorist travelled

wel

Average speed = total distance / time ⇒ total distance = average speed * time

Average speed = 270 km / p hours
distance = d
hours = x

d = 270/p * x

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3 years ago

What is fire department of the day

Andrej [43]

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3 years ago

Read 2 more answers

Two trains A and B of length 400 m each are moving on two parallel tracks with

Vinvika [58]

Answer:

The initial distance between the trains is 1450 m. 

Explanation:

In the question two trains are of equal length 400 m and moves at a uniform speed of 72 km/h. train A is moving ahead of train B. If the train B has to overtake train A it should accelerate.

Train B’s acceleration is $1m/s^2$ and it accelerated for 50 seconds.

 $a=1 m/s^2$ 

t=50 s 

initial speed u=72km/h 

we have to convert this speed into m/s 

 $u=72 \times 5/18=20 m/s$ 

Distance covered in accelerating phase $S=ut+1/2 at^2$ 

 $=20 \times 50+1/2 \times 1 \times 50^2$ 

 $=1000+1250=2250 m$ 

If a train is just behind another, the distance covered by the train located behind during overtaking phase will be equal to the sum of the lengths of the trains.

Here length of train A+length of train $B=400+400=800 m$ 

Hence the initial distance between the trains = $2250-800=1450 m$ 

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2 years ago

Please please help me, don't guess please my test is timed !!

dimulka [17.4K]

Answer:

a) J = F t = 40 * .05 = 2 N-s

b) J = 2 N-s momentum changed by 2 N-s

c) Initial momentum appears to be zero

J = change in momentum = m v2 - m v1 = m v2 = 2 N-s

v2 = J / m = 2 / .057 = 35 m/s

d) if the impulse time was increased and the average force remained the same then the change in momentum would increase with a corresponding increase in velocity attained - note the increase in v2 in part c)

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1 year ago