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Alex
3 years ago
12

How was helium first discovered?

Physics
2 answers:
Olenka [21]3 years ago
7 0

Answer:

using spectral analysis of the Suns’ emission spectra

Explanation:

lora16 [44]3 years ago
3 0
I think it’s the third one idk tho
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A 50-kg satellite circles the Earth in an orbit with a period of 120 min. What minimum energy is required to change the orbit to
uysha [10]

Answer: 2.94×10^8 J

Explanation:

Using the relation

T^2 = (4π^2/GMe) r^3

Where v= velocity

r = radius

T = period

Me = mass of earth= 6×10^24

G = gravitational constant= 6.67×10^-11

4π^2/GMe = 4π^2 / [(6.67x10^-11 x6.0x10^24)]

= 0.9865 x 10^-13

Therefore,

T^2 = (0.9865 × 10^-13) × r^3

r^3 = 1/(0.9865 × 10^-13) ×T^2

r^3 = (1.014 x 10^13) × T^2

To find r1 and r2

T1 = 120min = 120*60 = 7200s

T2 = 180min = 180*60= 10800s

Therefore,

r1 = [(1.014 x 10^13)7200^2]^(1/3) = 8.07 x 10^6 m

r2 = [(1.014 x 10^13)10800^2]^(1/3) = 10.57 x 10^6 m

Required Mechanical energy

= - GMem/2 [1/r2 - 1/r1]

= (6.67 x 10^-11 x 6.0 x 10^24 * 50)/2 * [(1/8.07 × 10^-6 )- (1/10.57 × 10^-6)]

= (2001 x 10^7)/2 * (0.1239 - 0.0945)

= (1000.5 × 10^7) × 0.0294

= 29.4147 × 10^7 J

= 2.94 x 10^8 J.

6 0
3 years ago
A tennis ball is thrown into
liraira [26]

Answer:

Velocity (v) is a vector quantity that measures displacement (or change in position, Δs) over the change in time (Δt), represented by the equation v = Δs/Δt. Speed (or rate, r) is a scalar quantity that measures the distance traveled (d) over the change in time (Δt), represented by the equation r = d/Δt.

Explanation:

7 0
2 years ago
Okay so I've have 10 Brainliest, through my whole time using brainly- I want people to get brainly and points so Im giving away
Nookie1986 [14]

answer:

thank youu for the points cute drawing by the way (✿◠‿◠)

when did you join brainly though?

have a wonderful dayyy !!

4 0
3 years ago
Read 2 more answers
A worker pushes a box across the floor to the right at a constant speed with a force of 25N. What
icang [17]

Answer:

Friction between the box and the floor is 25N to the left

Explanation:

There are two forces acting on the box along the horizontal direction:

- The force of push applied by the worker, in the forward direction, F

- The force of friction, F_f, acting in the opposite direction (backward)

So the net force acting on the box is

F_{net}=F-F_f

According to Newton's second law of motion, the net force on an object is equal to the product between its mass (m) and its acceleration (a), so we can write:

F_{net}=ma

And so

F-F_f = ma

However, in this case the box is moving at constant speed; this means that its acceleration is zero:

a=0

Therefore we have:

F-F_f=0

Which means

F_f=F

And since we are told that

F=25 N

This means that the force of friction is also 25 N:

F_f=F=25 N

6 0
3 years ago
Read 2 more answers
Help please
pychu [463]
The answer should be speed hope this helps

3 0
3 years ago
Read 2 more answers
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