Ask question

Ask question

All categories

3 years ago

8

The average height of an apple tree is 4.00 meters. How long would it take an apple falling from that height to reach the ground

? Given: g = -9.8 meters/second2

2 answers:

DENIUS [597]3 years ago

5 0

Answer:

The time is 0.90 sec.

Explanation:

Given that,

Height = 4.00 m

We need to calculate the time

Using equation of motion

$s = ut+\dfrac{1}{2}gt^2$

Where, s = height

g = acceleration due to gravity

t = time

Put the value into the formula

$4.00=0+\dfrac{1}{2}\times9.8\times t^2$

$t^2=\dfrac{4.00\times2}{9.8}$

$t=\sqrt{\dfrac{4.00\times2}{9.8}}$

$t=0.90\ sec$

Hence, The time is 0.90 sec.

denpristay [2]3 years ago

3 0

(9.8m/s) divided by 4m. the m's cancel out leaving you with s so 2.45s

You might be interested in

A truck moving at 36 m/s passes a police car moving at 45 m/s in the opposite direction. If the frequency of the siren is 500 Hz

wariber [46]

Answer:

change in frequency is 636 Hz

Explanation:

given data

speed v1 = 36 m/s

speed v2 = 45 m/s

frequency f = 500 Hz

speed of sound s = 343 m/s

to find out

what is the change in frequency

solution

we know here change of frequency formula that is

frequency = $\frac{s+v1}{s+v2}$ (f) ...................1

put here value in equation 1

and we take v2 = -45 because opposite direction

frequency = $\frac{s+v1}{s-v2}$ (f)

frequency = $\frac{343+36}{343-45}$ (500)

frequency = 636

so change in frequency is 636 Hz

8 0

4 years ago

There is a 247–m–high cliff at Half Dome in Yosemite National Park in California. Suppose a boulder breaks loose from the top of

Cerrena [4.2K]

Answer:

Vf = 69.61 m/s

Explanation:

We will use the third equation of motion to solve this problem:

$2gh = V_{f}^2 - V_{i}^2\\$

where,

g = acceleration due to gravity = 9.81 m/s²

h = height of cliff = 247 m

Vf = final velocity = ?

Vi = initial velocity = 0 m/s (boulder breaks loose from rest)

Therefore,

$(2)(9.81\ m/s^2)(247\ m) = V_{f}^2 - (0\ m/s)^2\\V_{f} = \sqrt{4846.14\ m^2/s^2}\\$

<u>Vf = 69.61 m/s</u>

8 0

3 years ago

Nine-year-old Dakoda realizes that the quantity of water in a glass remains the same, even when the water is poured into a diffe

Archy [21]

Answer:

Conservation

Explanation:

She has observation conservation because If the temperature of the liquids stays constant and the container is insulated and not heat or cool the liquid much would not change the density of the liquid very much so that it's original volume could remain constant.

The interesting thing is not that the child assumes the taller glass holds more liquid but that they fail to understand conservation: the fact that the water from one glass is going to be the same amount after being poured into any other container. It's as if they did not realize the water came from the same glass.

3 0

3 years ago

Imagine that the satellite described in the problem introduction is used to transmit television signals. You have a satellite TV

Korolek [52]

Complete Question

A satellite in geostationary orbit is used to transmit data via electromagnetic radiation. The satellite is at a height of 35,000 km above the surface of the earth, and we assume it has an isotropic power output of 1 kW (although, in practice, satellite antennas transmit signals that are less powerful but more directional).

Imagine that the satellite described in the problem introduction is used to transmit television signals. You have a satellite TV reciever consisting of a circular dish of radius R which focuses the electromagnetic energy incident from the satellite onto a receiver which has a surface area of 5 cm2.

How large does the radius R of the dish have to be to achieve an electric field vector amplitude of 0.1 mV/m at the receiver?

For simplicity, assume that your house is located directly beneath the satellite (i.e. the situation you calculated in the first part), that the dish reflects all of the incident signal onto the receiver, and that there are no losses associated with the reception process. The dish has a curvature, but the radius R refers to the projection of the dish into the plane perpendicular to the direction of the incoming signal.

Give your answer in centimeters, to two significant figures.

Answer:

The radius of the dish is $R = 18cm$

Explanation:

From the question we are told that

The radius of the orbit is = $R = 35,000km = 35,000 *10^3 m$

The power output of the power is $P = 1 kW = 1000W$

The electric vector amplitude is given as $E = 0.1 mV/m = 0.1 *10^{-3}V/m$

The area of thereciever is $A_R = 5cm^2$

Generally the intensity of the dish is mathematically represented as

$I = \frac{P}{A}$

Where A is the area orbit which is a sphere so this is obtained as

$A = 4 \pi r^2$

$= (4 * 3.142 * (35,000 *10^3)^2)$

$=1.5395*10^{16} m^2$

Then substituting into the equation for intensity

$I_s = \frac{1000}{1.5395*10^{16}}$

$= 6.5*10^ {-14}W/m2$

Now the intensity received by the dish can be mathematically evaluated as

$I_d = \frac{1}{2} * c \epsilon_o E_D ^2$

Where c is thesped of light with a constant value $c = 3.0*10^8 m/s$

$\epsilon_o$ is the permitivity of free space with a value $8.85*10^{-12} N/m$

$E_D$ is the electric filed on the dish

So since we are to assume to loss then the intensity of the satellite is equal to the intensity incident on the receiver dish

Now making the eletric field intensity the subject of the formula

$E_D = \sqrt{\frac{2 * I_d}{c * \epsilon_o} }$

substituting values

$E_D = \sqrt{\frac{2 * 6.5*10^{-14}}{3.0*10^{8} * 8.85*10^{-12}} }$

$= 7*10^{-6} V/m$

The incident power on the dish is what is been reflected to the receiver

$P_D = P_R$

Where $P_D$ is the power incident on the dish which is mathematically represented as

$P_D = I_d A_d$

$= \frac{1}{2} c \epsilon_o E_D^2 (\pi R^2)$

And $P_R$ is the power incident on the dish which is mathematically represented as

$P_R = I_R A_R$

$= \frac{1}{2} c \epsilon_o E_R^2 A_R$

Now equating the two

$\frac{1}{2} c \epsilon_o E_D^2 (\pi R^2) = \frac{1}{2} c \epsilon_o E_R^2 A_R$

Making R the subject we have

$R = \sqrt{\frac{E_R^2 A_R}{\pi E_D^2} }$

Substituting values

$R = \sqrt{\frac{(0.1 *10^{-3})^2 * 5}{\pi (7*10^{-6})^ 2} }$

$R = 18cm$

8 0

3 years ago

Which factor (s) have the most affect a person’s vital capacity? Rank in order from MOST effect (1) to least effect (5)

jenyasd209 [6]

The factors that affect vital capacity are :

Age
Sex
Height
Body mass
Ethnicity

Explanation:

Vital capacity is the maximum amount of air that a person can exhale once he has filled his lungs with maximum air. So, it is like maximum exhalation after maximum inhalation by a person.

Vital capacity is also equal to Forced Vital Capacity.

Lung usually have their maximum capacity in early adult days and this capacity reduces as the person grows older. So age is the prime factor in this.

A female with same age and height as that of male will have 10-12% less vital capacity than him. So sex is another reason which determines vital capacity.

Person with more height has more vital capacity. This is because lungs capacity is closely related to the third power of person's height.

Person suffering from obesity will have compressed diaphragm, lung and chest cavity , so their vital capacity will be less. So we can say body mass affects vital capacity.

Last factor, ethnicity, is yet to be understood clearly as there is not much evidence of this.

3 0

3 years ago