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Anvisha [2.4K]
4 years ago
15

Which statement is true? A) All waves travel at the same speed through any medium. B) All waves travel at the same speed if no m

edium is present. C) Electromagnetic waves require a medium, but mechanical waves do not. D) Mechanical waves require a medium, but electromagnetic waves do not. Eliminate
Physics
2 answers:
Keith_Richards [23]4 years ago
8 0
I just took the test and it D . have a good day
zhannawk [14.2K]4 years ago
5 0
D) Mechanical waves always require a medium, while electromagnetic waves do not and can thus travel through open space.
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What is the car's average velocity (in m/s) in the interval between t = 1.0 s<br> to t = 1.5 s?
natali 33 [55]

Answer:

1.4 m/s

Explanation:

From the question given above, we obtained the following data:

Initial Displacement (d1) = 0.9 m

Final Displacement (d2) = 1.6 m

Initial time (t1) = 1.5 secs

Final time (t2) = 2 secs

Velocity (v) =..?

The velocity of an object can be defined as the rate of change of the displacement of the object with time. Mathematically, it can be expressed as follow:

Velocity = change of displacement /time

v = Δd / Δt

Thus, with the above formula, we can obtain the velocity of the car as follow:

Initial Displacement (d1) = 0.9 m

Final Displacement (d2) = 1.6 m

Change in displacement (Δd) = d2 – d1 = 1.6 – 0.9

= 0.7 m

Initial time (t1) = 1.5 secs

Final time (t2) = 2 secs

Change in time (Δt) = t2 – t1

= 2 – 1.5

= 0.5 s

Velocity (v) =..?

v = Δd / Δt

v = 0.7/0.5

v = 1.4 m/s

Therefore, the velocity of the car is 1.4 m/s

4 0
3 years ago
What is the kinetic energy of a 150 gram object moving at a velocity of 100 m/s?
Alex Ar [27]

Answer:

750 J

Explanation:

lets convert mass into kg first , 150 /1000 = 0.15 kg

kinetic energy =  \frac{mv^{2} }{2} =  \frac{0.15*100^{2} }{2}  = 750 J

3 0
3 years ago
A railroad track and a road cross at right angles. An observer stands on the road and watches an eastbound train traveling at 60
mamaluj [8]

Answer:

After 4 s of passing through the intersection, the train travels with 57.6 m/s

Solution:

As per the question:

Suppose the distance to the south of the crossing watching the east bound train be x = 70 m

Also, the east bound travels as a function of time and can be given as:

y(t) = 60t

Now,

To calculate the speed, z(t) of the train as it passes through the intersection:

Since, the road cross at right angles, thus by Pythagoras theorem:

z(t) = \sqrt{x^{2} + y(t)^{2}}

z(t) = \sqrt{70^{2} + 60t^{2}}

Now, differentiate the above eqn w.r.t 't':

\frac{dz(t)}{dt} = \frac{1}{2}.\frac{1}{sqrt{3600t^{2} + 4900}}\times 2t\times 3600

\frac{dz(t)}{dt} = \frac{1}{sqrt{3600t^{2} + 4900}}\times 3600t

For t = 4 s:

\frac{dz(4)}{dt} = \frac{1}{sqrt{3600\times 4^{2} + 4900}}\times 3600\times 4 = 57.6\ m/s

4 0
3 years ago
Which mixtures could be separated using evaporation? Check all that apply. fat in milk salt in ocean water mud in pond water but
salantis [7]
I would go with salt in ocean water as when you heat it and the water begins to evaporate it will leave the salt behind


Also water in mud as the water would evaporate and leave the mud residue behind


GOOD LUCK
BRAINLIEST IF HELPED
5 0
4 years ago
Read 2 more answers
Jerry runs 60 meters east and then 20 meters west in 10
liraira [26]

Answer: 8 meters per second

Explanation: If you add 60 to 20 you get 80 meters and since he ran those 80 meters in 10 seconds you divide 80 by ten and get 8 and then you get 8m/s

4 0
3 years ago
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