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3 years ago

13

Why does a truck that is traveling in the opposite direction to you on the street appear to be moving faster than it would if yo

u were not moving?

1 answer:

svet-max [94.6K]3 years ago

5 0

Hmmm...maybe it would be because since you're staying still then things appear to go by quickly.

You might be interested in

Considering how the parts of a system work together and affect one another, other systems, and the environment is called _______

-BARSIC- [3]

Answer:

Hi

before I answer a question I think very deeply and try my best, hope it helps...

As you know there are many different types of systems. For example, The solar system, galaxies, quantum systems, atoms, molecules, orchestras, nervous system, etc, things you may not have even considered a system. To get to the basis of a system we must first understand what a system is then we will show some examples. A system is a group of Parts (parts could mean anything even dark energy and dark matter) that work together to accomplish something. For example, your body has many many trillions of cells that all try to accomplish the functions of humans which include thinking, moving, breathing, circulation, etc. Cells in turn are a system that have counterparts called organelles that accomplish harvesting energy, making new proteins, getting rid of waste, and so on. These are some systems which we highly dependent upon.

Well i hope it helped

Spiky Bob your answerer

8 0

3 years ago

Very far from earth (at R- oo), a spacecraft has run out of fuel and its kinetic energy is zero. If only the gravitational force

Margaret [11]

Answer:

Speed of the spacecraft right before the collision: $\displaystyle \sqrt{\frac{2\, G\cdot M_\text{e}}{R\text{e}}}$ .

Assumption: the earth is exactly spherical with a uniform density.

Explanation:

This question could be solved using the conservation of energy.

The mechanical energy of this spacecraft is the sum of:

the kinetic energy of this spacecraft, and
the (gravitational) potential energy of this spacecraft.

Let $m$ denote the mass of this spacecraft. At a distance of $R$ from the center of the earth (with mass $M_\text{e}$ ), the gravitational potential energy ( $\mathrm{GPE}$ ) of this spacecraft would be:

$\displaystyle \text{GPE} = -\frac{G \cdot M_\text{e}\cdot m}{R}$ .

Initially, $R$ (the denominator of this fraction) is infinitely large. Therefore, the initial value of $\mathrm{GPE}$ will be infinitely close to zero.

On the other hand, the question states that the initial kinetic energy ( $\rm KE$ ) of this spacecraft is also zero. Therefore, the initial mechanical energy of this spacecraft would be zero.

Right before the collision, the spacecraft would be very close to the surface of the earth. The distance $R$ between the spacecraft and the center of the earth would be approximately equal to $R_\text{e}$ , the radius of the earth.

The $\mathrm{GPE}$ of the spacecraft at that moment would be:

$\displaystyle \text{GPE} = -\frac{G \cdot M_\text{e}\cdot m}{R_\text{e}}$ .

Subtract this value from zero to find the loss in the $\rm GPE$ of this spacecraft:

$\begin{aligned}\text{GPE change} &= \text{Initial GPE} - \text{Final GPE} \\ &= 0 - \left(-\frac{G \cdot M_\text{e}\cdot m}{R_\text{e}}\right) = \frac{G \cdot M_\text{e}\cdot m}{R_\text{e}} \end{aligned}$

Assume that gravitational pull is the only force on the spacecraft. The size of the loss in the $\rm GPE$ of this spacecraft would be equal to the size of the gain in its $\rm KE$ .

Therefore, right before collision, the $\rm KE$ of this spacecraft would be:

$\begin{aligned}& \text{Initial KE} + \text{KE change} \\ &= \text{Initial KE} + (-\text{GPE change}) \\ &= 0 + \frac{G \cdot M_\text{e}\cdot m}{R_\text{e}} \\ &= \frac{G \cdot M_\text{e}\cdot m}{R_\text{e}}\end{aligned}$ .

On the other hand, let $v$ denote the speed of this spacecraft. The following equation that relates $v\!$ and $m$ to $\rm KE$ :

$\displaystyle \text{KE} = \frac{1}{2}\, m \cdot v^2$ .

Rearrange this equation to find an equation for $v$ :

$\displaystyle v = \sqrt{\frac{2\, \text{KE}}{m}}$ .

It is already found that right before the collision, $\displaystyle \text{KE} = \frac{G \cdot M_\text{e}\cdot m}{R_\text{e}}$ . Make use of this equation to find $v$ at that moment:

$\begin{aligned}v &= \sqrt{\frac{2\, \text{KE}}{m}} \\ &= \sqrt{\frac{2\, G\cdot M_\text{e} \cdot m}{R_\text{e}\cdot m}} = \sqrt{\frac{2\, G\cdot M_\text{e}}{R_\text{e}}}\end{aligned}$ .

6 0

3 years ago

A chair exerts a force of 20 N on a floor and is not moving. What force does

AysviL [449]

The floor exerts 20 N of force on the chair

Explanation:

We can answer this question by using Newton's third law, which states that:

<em>"When an object A exerts a force (called action) on an object B, object B exerts an equal and opposite force (called reaction) on object A"</em>

In this problem, we can identify:

- Object A as the chair

- Object B as the floor

This means that the force of 20 N exerted by the chair on the floor is the action, and so the force exerted by the floor on the chair is the reaction. Newton's third law states that these two forces are equal and opposite: therefore, the force exerted by the floor on the chair is also 20 N, but in the opposite direction.

Learn more about Newton's third law:

brainly.com/question/11411375

#LearnwithBrainly

8 0

3 years ago

A ball is thrown at 60 degrees and lands in 18.5 seconds what is the velocity of the ball at the start

n200080 [17]

Answer:

the initial velocity of the ball is 104.67 m/s.

Explanation:

Given;

angle of projection, θ = 60⁰

time of flight, T = 18.5 s

let the initial velocity of the ball, = u

The time of flight is given as;

$T = \frac{2u\times sin(\theta)}{g} \\\\2u\times sin(\theta) = Tg\\\\u = \frac{Tg}{2\times sin(\theta)} \\\\u = \frac{18.5 \times 9.8}{2\times sin(60^0)} \\\\u = 104.67 \ m/s$

Therefore, the initial velocity of the ball is 104.67 m/s.

3 0

3 years ago

Some people wish that we lived in a recollapsing universe that would eventually stop expanding and start contracting. For this t

Monica [59]

Answer:

(B) Dark energy does not exist and there is much more matter than current evidence suggests.

Explanation:

The repulsive force which is accelerating expansion of the universe is called as dark energy. Most of matter present in the universe is the dark matter of about eighty five percent.

So, a collapsing universe would not have the dark energy and there is more matter which is not the dark matter. This theory is rejected because expansion of the universe is observable.

4 0

4 years ago