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3 years ago

. What is the mass number of the isotope lithium-7?

Physics

2 answers:

Alex17521 [72]3 years ago

7 0

Answer:

Explanation:

isotopes are named after there mass number. because there mass number is different and protons no is same

lana66690 [7]3 years ago

4 0

Answer:

Explanation:

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A student discovers that sound waves travel 1,687.5 meters in 5 seconds through air at a temperature of 10°C. Based on this info

vitfil [10]

Answer:

The speed of sound, in m/s, through air at this temperature is 343.5 m/s

Explanation:

Given;

distance traveled by sound, d = 1,687.5 meters

time taken for the sound to travel, t = 5 seconds

air temperature, θ = 10°C

Speed of sound = distance traveled by sound / time taken for the sound to travel

Speed of sound = d / t

= 1687.5 m / 5 s

= 337.5 m/s

Speed of sound at the given temperature is calculated as;

c = 337.5 + 0.6θ

c = 337.5 + 0.6 x 10

c = 337.5 + 6

c = 343.5 m/s

Therefore, the speed of sound, in m/s, through air at this temperature is 343.5 m/s

8 0

3 years ago

A block is held at rest against a wall by a force of magnitude F exerted at an angle theta from the horizontal, as shown in the

wel

Answers:

B.) $F cos\theta=F_{n}$

C.) $F sin\theta=F_{g} \pm F_{f}$

Explanation:

The image attached shows the way the force $F$ is acting on the block. Now, if we draw a free body diagram of the situation and write the equations for the Net Force in X and Y, we will have the following:

Net Force in X:

$-F_{n}+F cos\theta=0$ (1)

Where:

$F_{n}$ is the Normal force

$F$ is the magnitude of the force exerted on the block

$\theta$ is the angle

Net Force in Y:

$F sin\theta \pm F_{f}-F_{g}=0$ (2)

Where:

$F_{f}$ is the Friction force (it is expresed with the $\pm$ sign because this force may be up or down, we cannot know because the block is at rest)

$F_{g}$ is the gravity force

Rewrittin (1):

$F cos\theta=F_{n}$ (3) This is according to option B

Rewritting (2):

$F sin\theta=F_{g}\pm F_{f}$ (3) This is according to option C

3 0

3 years ago

Is the ratio between the sine of an angle of incidence to the sine of an angle of refraction is called the refractive index?

motikmotik

Answer:

Yes

Explanation:

Yes it is called the refractive index denoted by n

n=sin<i/sin<r

6 0

3 years ago

Read 2 more answers

What is time write its SI unit

lisabon 2012 [21]

The SI unit of time is second

4 0

3 years ago

Which vector is the sum of vectors a and ? b а O A. B. C.

seropon [69]

Answer:

i would say D.

Explanation:

5 0

3 years ago