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3 years ago

Why are objects that fall near Earth's surface rarely in free fall?

Physics

1 answer:

sveta [45]3 years ago

6 0

Answer: Air exerts forces on falling objects near Earth's surface.

Explanation: Objects falling near the earth surface are rarely in free fall due to the force exerted by air on falling object near the earth( air resistance).

The acceleration of free fall tend to pull the body towards the earth surface while air resistance (drag) tends to act in the opposite direction.

Given that the weight of the body is always constant.

The drag acts in the upward direction, thereby negating the downward weight of the object.

From Newton's Second law:

Force = mass × acceleration due to gravity

Acceleration = force / mass

The net force acting on the object becomes :

(Downward weight - upward drag)

This hampers the free fall of the object due to gravity.

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When you observe a distant galaxy whose photons have traveled for 10 billion years before reaching earth we are seeing that gal?

expeople1 [14]

In reality we don't see the galaxy we see it's reflection .. the light hits or got emitted by the star travel all the way long to hit our eyes .. we see their reflection . everything around you that you see is it's reflection

8 0

3 years ago

A sinusoidal wave has the following wave function: y(x,t) = (2.5 m) sin((3.0 m ) x - (24 s-')t + Tt/2] What is the frequency of

vladimir1956 [14]

Answer:

Frequency of the wave is 3.8 hertz.

Explanation:

It is given that, the sinusoidal wave has following wave equation as :

$y(x,t)=(2.5\ m)sin[(3\ m^{-1})x-(24\ s^{-1})t+\pi/2]$

The general equation for the sinusoidal wave is :

$y=A\ sin(kx-\omega t+\phi)$

Where

A is the amplitude

k is the constant

$\omega$ is the angular frequency

$\phi$ is the phase difference

Since, $\omega=24\ s^{-1}$

$2\pi f=24$

$f=\dfrac{24}{2\pi}=3.81\ Hz$

f = 3.8 Hz

So, the frequency of the wave is 3.8 hertz. Hence, this is the required solution.

8 0

3 years ago

A cat lies on the floor. can you say that no force acts on the cat? or is it correct to say that no net force acts on the cat? e

DIA [1.3K]

Odd though it seems at first, gravity is pulling the cat down while the floor is pushing the cat up - in equal amounts. Forces are absolutely acting on the cat but they balance - so there is no net force.

5 0

3 years ago

When you're asked to calculate moments and torque, what's the main difference in calculation? Also what is a couple?

leva [86]

Answer:

a) Explanation below. b) Explanation below

Explanation:

Torque is defined as the product of a force by a radius, while momentum is defined as the product of force by a distance. Mathematically we would have

T = F * r

M = F * d

where:

T = torque = [N*m]

M = moment = [N*m]

F = force =[N]

d = distance [m]

r = radius [m]

Although they have the same units, the difference between them is the application. For the case of torque this is always applied in parts that are in rotation, such as the shafts of cars, the shafts of pumps, torque in gears and etc. While the moment can be applied to a body without the need for it to rotate.

A couple, is as its name suggests a couple of forces of equal magnitude but opposite sense and do not share a line of action. A body under the action of a couple of forces tends to rotate the body without moving it from one point to another.

7 0

3 years ago

When t= 1 a stone B is thrown vertically upwards from ground level with speed 5ms (ii) find t when a and b collide

Ksju [112]

Answer:

i don't know if this is good for you but

Explanation:

ignoring frictional air resistance (drag) the speed on return is the same as when it left the ground (5 m/s but in the opposite direction).

Note: this points out a good reason for not firing live bullets into the air..they will return somewhere and at the same speed.

However, if you take into account the atmospheric drag the reurn speed will be somewhat smaller (but in the case of a bullet, probably still lethal.) Drag depends on many factors and is difficult to calculate.

5 0

3 years ago