All categories

4 years ago

Help plz I don't understand

Physics

1 answer:

Vika [28.1K]4 years ago

6 0

#78

Airplane start with initial speed

$v_i = 0$

now the takeoff velocity is given as

$v_f = 300 km/h$

$v_f = 83.33 m/s$

acceelration is given as

$a = 1 m/s^2$

now we have

$v_f - v_i = at$

from above equation we have

$83.33 - 0 = 1(t)$

$t = 83.33 s$

#79

Airplane start with initial speed

$v_i = 0$

now the takeoff velocity is given as

$v_f = 300 km/h$

$v_f = 83.33 m/s$

acceelration is given as

$a = 2 m/s^2$

now we have

$v_f - v_i = at$

from above equation we have

$83.33 - 0 = 2(t)$

$t = 41.7 s$

You might be interested in

Calculate the height from which a body is released from rest if its velocity just before hitting the ground is 30ms

nexus9112 [7]

S= ?
U= 0 $ms^{-1}$
V= 30 $ms^{-1}$
A= 9.8 $ms^{-2}$
T=

$V^2 = U^2 + 2AS$
$900 = 19.6S$
$\frac{900}{19.6} = S$
S = 45.92 $m$

6 0

4 years ago

Can someone help with these/

mafiozo [28]

One

If you use the right hand rule for these problems, you usually make your fingers and thumb sit at right angles to each other. What each of the two fingers means and that related to the thumb is a different story. All you have to understand at this point is that all three are mutually perpendicular.

That makes C the answer.

All the other choices don't make that clear.

Two

This is a straight definition question. The definition says exactly what D says.

5 0

4 years ago

Calculate the voltage difference in a circuit that has a resistance of 24 if the current is 0.50 a

bixtya [17]

In order to calculate the voltage difference in the circuit, we need to look at the equation: V=IR.

In the equation:

V= Voltage

I= Current

R= Resistance.

Assuming we know this, We will plug it into an equation to find our voltage.

V=(.50a)x(24Ω)

If we solve for V, Your final answer will be: 12v (or 12 volts)

6 0

3 years ago

In a real isothermal expansion, the temperature of the surroundings must be________the temperature of the gas.

Lady_Fox [76]

Must be isolated from the temperature of the gas

7 0

3 years ago

A newly discovered planet is found to have a density if 2/3pe and a radius of 2RE, where PE and RED are the density and radius o

Liono4ka [1.6K]

Missing question in the text of the exercise. Found on internet:
"What is the acceleration due to gravity on the surface of the planet?"

Solution:
The gravitational acceleration at Earth's surface is given by:
$g= \frac{GM}{r^2}$
where
G is the gravitational constant
M is the Earth's mass
r is the Earth's radius

The Earth's mass can be rewritten also as the product between the Earth's density, $d$ , and its volume (the volume of a sphere of radius r):
$M=dV=d ( \frac{4}{3} \pi r^3)= \frac{4}{3} \pi d r^3$

Now let's call M' the mass of the new planet, r' its radius and d' its density. The acceleration due to gravity on the surface of the new planet is
$g' = \frac{GM'}{r'^2}$ (1)
so we need to find M' and r'.

The problem says the radius of the new planet is twice the Earth's radius:
$r'=2r$ (2)
and that its density is 2/3 of Earth's density:
$d'= \frac{2}{3} d$
so the mass M' of the new planet is, with respect to the Earth's mass:
$M' = d'V' = \frac{4}{3} \pi d' (r')^3 = \frac{4}{3} \pi ( \frac{2}{3}d) (2r)^3 = ( \frac{4}{3} \pi d r^3 )( \frac{16}{3}) = \frac{16}{3} M$ (3)

And if we substitute (2) and (3) into (1), we find the gravitational acceleration on the surface of the new planet:
$g'= \frac{G( \frac{16}{3}M) }{(2r)^2}= \frac{GM}{r^2} \frac{4}{3} = \frac{4}{3}g$
And since $g=9.81 m/s^2$ , we find
$g'= \frac{4}{3}(9.81 m/s^2)=13.1 m/s^2$

8 0

3 years ago

Help plz I don't understand ​

Help plz I don't understand