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3 years ago

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A man standing on a bus remains still when the bus is at rest. When the bus moves forward and then slows down the man continues

moving forward at the original speed. This is an example of the effect of
A. weight.
B. gravity.
C. inertia.
D. velocity.

1 answer:

Stells [14]3 years ago

6 0

C. inertia. the man is sent flying off the bus because of his weight and the sudden stop of the bus. this effect is called inertia. an example of gravity would be throwing an apple up and having it come to the ground. an example of weight would be putting a man and an elephant on a scale and having the elephant come down while the man goes up.

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You stand at the top of a deep well. To determine the depth, D, of the well you drop a rock from the top of the well and listen

Paladinen [302]

Answer:

(A)

$\displaystyle D^2-\left (\frac{2v_s^2}{g}+2t_tv_s \right )D+t_t^2v_s^2=0$

<em>(B) D=54.71 m</em>

Explanation:

<u>Free Fall</u>

When a particle is dropped in free air, it starts falling to the ground with an acceleration equal to the gravity. If one wanted to know the height of launching, it can indirectly be measured by the time it takes to reach the ground by the formula

$\displaystyle D=\frac{gt^2}{2}$

Solving for t

$\displaystyle t=\sqrt{\frac{2D}{g}}$

If we are taking into consideration the time we can hear the sound it makes when hitting the ground (or water in this case), we must also consider the speed of the sound for the time it takes to reach back our ears. That time can be computed from the basic equation for the speed

$\displaystyle t=\frac{D}{v_s}$

(A)

The total measured time is the sum of both times and it's given as $t_t=3.5\ seconds$

$\displaystyle t_t=\sqrt{\frac{2D}{g}}+\frac{D}{v_s}$

From this equation we'll manage to compute D

First, we isolate the square root

$\displaystyle \sqrt{\frac{2D}{g}}=t_t-\frac{D}{v_s}$

Let's square both sides

$\displaystyle \frac{2D}{g}=t_t^2-2t_t\frac{D}{v_s}+\frac{D^2}{v_s^2}$

Multiplying by $v_s^2$

$\displaystyle \frac{2Dv_s^2}{g}=t_t^2v_s^2-2t_tDv_s+D^2$

Rearranging and factoring

$\boxed{\displaystyle D^2-\left (\frac{2v_s^2}{g}+2t_tv_s\right )D+t_t^2v_s^2=0}$

Now, let's put in numbers:

$g=9.8\ m/s^2,\ v_s=345\ m/s,t_t=3.5\ sec$

$\displaystyle D^2-\left (\frac{2(345)^2}{9.8}+2(3.5)(345)\right )D+(12.25)345^2=0$

Computing all the coefficients:

$\displaystyle D^2-26,705.82D+1,458,056.25=0$

Solving for D, we have two possible solutions:

$D=54.71,\ D=26,651.11$

The second solution is called "extraneous", since it comes from squaring an equation, which can introduce non-valid (or external) solutions. It's impossible, given the conditions of the problem, that the well could be 26.5 km deep. So we'll keep the only solution as.

<em>D=54.71 m</em>

Let's prove our calculations by computing both times:

$\displaystyle t_1=\sqrt{\frac{2(54.71)}{9.8}}=3.34\ sec$

$\displaystyle t_2=\frac{54.71}{345}=0.16\ sec$

We can see their sum is 3.5 seconds, 3.34 of which were taken to reach the bottom of the well, and 0.16 sec took the sound to reach the top.

3 0

3 years ago

Which can be observed both on Earth and in an accelerating ship in space that is free from the effect of any gravitational field

Reil [10]

Answer:

apples falling from trees
people's feet touching the ground
sky divers moving toward the ground
balls bending downward after being thrown

Explanation:

When a space ship is accelerating in space, there is a force known as Inertia that kicks in. Inertia will mirror the effects of gravity on the ship even if there is no gravitational field effect such that anything that would happen where there is gravity, would continue to happen.

This means that apples will fall from trees, people's feet will touch the ground, sky divers will be pulled downwards and balls will bend downwards when thrown as well. These are the same effects expected on earth where gravity pulls things towards the earth's core.

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2 years ago

Read 2 more answers

A proton with a speed of 3.2 x 106 m/s is shot into a region between two plates that are separated by a distance of 0.23 m. As t

harina [27]

Answer:

<h2>The magnitude of the magnetic is 0.145 T</h2>

Explanation:

Given :

Speed of proton $v = 3.2 \times 10^{6}\frac{m}{s}$

Mass of proton $m = 1.67 \times 10^{-27}$ Kg

The force on the proton in magnetic field is given by,

$F = q (v \times B)$

$F = qvB \sin \theta$

But $\sin 90 = 1$ (∵ Force is perpendicular to the velocity so $\theta = 90$ )

$F = qvB$

When particle enter in magnetic field at the angle of 90° so particle moves in circle

So force is given by,

$F = \frac{mv^{2} }{r}$

Where $r =$ radius but in our case 0.23 m, $q = 1.6 \times 10^{-19}$ C

By comparing above two equation,

$B = \frac{mv}{qr}$

$B = \frac{1.67 \times 10^{-27} \times 3.2 \times 10^{6} }{1.6 \times 10^{-19} \times 0.23 }$

$B = 0.145$ T

5 0

3 years ago

What is projectile motion caused by?

Lemur [1.5K]

Gravity acts to influence the vertical motion of the projectile, thus causing a vertical acceleration. The horizontal motion of the projectile is the result of the tendency of any object in motion to remain in motion at constant velocity.

6 0

3 years ago

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A sound wave travelling in water has a frequency of 100 Hz. The speed of sound in water is 1482 m/s. Calculate the wavelength of

xz_007 [3.2K]

Steps : The formula for wavelength is:
λ = v/f
λ = 1482/100

Answer:

λ = 14.82 m

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2 years ago