Ask question

Ask question

All categories

3 years ago

13

A ball is dropped off a roof. The ball falls for 4 seconds. Just before the ball hits the ground what is its velocity?

1 answer:

scZoUnD [109]3 years ago

7 0

Answer:

<em>The velocity is 39.24 m/s</em>

<em></em>

Explanation:

The time of fall t = 4 seconds

The initial velocity u = 0 m/s (since the ball is dropped, meaning it starts from rest)

Final velocity v = ?

Using

v = u + gt

where g is the acceleration due to gravity = 9.81 m/s^2

substituting, we'll have

v = 0 + (9.81 x 4)

v = <em>39.24 m/s</em>

You might be interested in

How does an executive order differ from a statue?

ICE Princess25 [194]

Answer: Executive Order on Protecting American Monuments, Memorials, and Statues against our country are public monuments, memorials, and statues.

Explanation: learned it last week

6 0

2 years ago

A wildlife photographer uses a moderate telephoto lens of focal length 135 mm and maximum aperture f/4.00 to photograph a bear t

labwork [276]

Answer:

<h3>(A) The width $x = 0.24 \times 10^{-3}$ m</h3><h3>(B) The new width is $1.32 \times 10^{-3}$ m</h3>

Explanation:

Given :

Focal length $f = 135 \times 10^{-3} m$

Maximum aperture $D = \frac{f}{4}$

Wavelength $\lambda = 550 \times 10^{-9}$ m

(A)

From rayleigh criterion,

$\theta = \frac{1.22 \lambda }{D}$

$\theta =\frac{ 1.22 \times 550 \times 10^{-9} }{33.75 \times 10^{-3} }$

$\theta = 1.98 \times 10^{-5}$ rad

From angle formula,

$x = R\theta$

Where $R =$ 12 m ( given in example )

$x = 12 \times 1.98 \times 10^{-5}$ m

$x = 23.76 \times 10^{-5}$

$x = 0.24 \times 10^{-3}$ m

(B)

We know that $\theta$ is proportional to the $x$ and inversely proportional to the $D$

so we write the new width, here $x$ is 5.5 times larger than above case

$x = 0.24 \times 10^{-3} \times \frac{22}{4}$

$x = 1.32 \times 10^{-3}$ m

6 0

2 years ago

Radiation from the Sun reaching Earth (just outside the atmosphere) has an intensity of 1.39 kW/m2. (a) Assuming that Earth (and

Zigmanuir [339]

Answer:

$F=5.8\times 10^{8}\ N$

$F=35.57\times 10^{21}\ N$

Explanation:

Given that

Intensity I

$I= 1.39\ KW/m^2$

$Speed\ of \ light = 2.99\times 10^8\ m/s$

Radius of earth,R = 6370 Km

We know that surface area of earth, A

$A=\pi R^2$

$A=\pi (6370\times 10^3)^2\ m^2$

$A=1.27\times 10^{14}\ m^2$

As we know that pressure due to intensity given as

$P=\dfrac{I}{V}$

V =Velocity of light

$V=3\times 10^8\ m/s$

$P=\dfrac{1.39\times 1000}{=3\times 10^8}$

$P=4.6\times 10^{-6}\ Pa$

We know that force F

F = P .A

$F=4.6\times 10^{-6}\times 1.27\times 10^{14}\ N$

$F=5.8\times 10^{8}\ N$

b)Gravitational force F

$F=G\dfrac{m.M}{r^2}$

$M = mass\ of\ sun = 2\times 10^{30} kg\\m = mass\ of\ earth = 6\times 10^{24}kg$

$r =1.5\times 10^{11}\ m$

$G =6.67\times 10^{-11}Nm^2/kg^2$

So F

$F=6.67\times 10^{-11}\times \dfrac{2\times 10^{30}\times 6\times 10^{24}kg}{1.5\times 10^{11}}$

$F=35.57\times 10^{21}\ N$

7 0

3 years ago

Read 2 more answers

3. An ecosystem is different from all of

charle [14.2K]

Answer:

I think it is O only nonliving

5 0

3 years ago

Read 2 more answers

Which statement is true of forces?

jasenka [17]

FORCES HAVE STRENGTH AND DIRECTION

8 0

2 years ago