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3 years ago

Please help!!!!! :)

Physics

2 answers:

kow [346]3 years ago

5 0

The answer is A because bases are greater than 7 and acids are lower than 7

Jlenok [28]3 years ago

4 0

What's up ? ! ? You should know most of these.

RbOH is a base because its PH is greater than 7.

Sulfur trioxide is SO₃ .

Mixtures B, C, and D can be separated by distillation.
Pebbles and sand can't.

If some salt is dissolved in a beaker of water, then
the salt is the solute and the water is the solvent.

The equation is not balanced because the number of atoms
of each element on the left is not equal to the number of atoms
of that element on the right.
In fact, the total number of all atoms on the left (8) is not even
equal to the total number of all atoms on the right (10).

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What is the resistance force when you walk up an inclined plane?<br> Please help quick!

Dominik [7]

Friction
Friction also affects the movement of an object on a slope. Friction is a force that offers resistance to movement when one object is in contact with another. Imagine now that you were on the downside of the object and applying force to keep the object in the same place (not moving)

5 0

3 years ago

Tim and Rick both can run at speed Vr and walk at speed Vw, with Vr > Vw.

miss Akunina [59]

Answer:

Δt = $\frac{2D}{Vw+Vr} - \frac{D}{2Vr} - \frac{D}{2Vw}$

Explanation:

Hi there!

Using the equation of speed for the whole trip, we can obtain the time each one needed to cover the distance D.

The speed (v) is calculated by dividing the traveled distance (d) over the time needed to cover that distance (t):

v = d/t

Rick traveled half of the distance at Vr and the other half at Vw. Then, when v = Vr, the distance traveled was D/2 and the time is unknown, Δt1:

Vr = D/ (2 · Δt1)

For the other half of the trip the expression of velocity will be:

Vw = D/(2 · Δt2)

The total time traveled is the sum of both Δt:

Δt(total) = Δt1 + Δt2

Then, solving the first equation for Δt1:

Vr = D/ (2 · Δt1)

Δt1 = D/(2 · Vr)

In the same way for the second equation:

Δt2 = D/(2 · Vw)

Δt + Δt2 = D/(2 · Vr) + D/(2 · Vw)

Δt(total) = D/2 · (1/Vr + 1/Vw)

The time needed by Rick to complete the trip was:

Δt(total) = D/2 · (1/Vr + 1/Vw)

Now let´s calculate the time it took Tim to do the trip:

Tim walks half of the time, then his speed could be expressed as follows:

Vw = 2d1/Δt Where d1 is the traveled distance.

Solving for d1:

Vw · Δt/2 = d1

He then ran half of the time:

Vr = 2d2/Δt

Solving for d2:

Vr · Δt/2 = d2

Since d1 + d2 = D, then:

Vw · Δt/2 + Vr · Δt/2 = D

Solving for Δt:

Δt (Vw/2 + Vr/2) = D

Δt = D / (Vw/2 + Vr/2)

Δt = D/ ((Vw + Vr)/2)

Δt = 2D / (Vw + Vr)

The time needed by Tim to complete the trip was:

Δt = 2D / (Vw + Vr)

Let´s find the diference between the time done by Tim and the one done by Rick:

Δt(tim) - Δt(rick)

2D / (Vw + Vr) - (D/2 · (1/Vr + 1/Vw))

$\frac{2D}{Vw+Vr} - \frac{D}{2Vr} - \frac{D}{2Vw}$ = Δt

Let´s check the result. If Vr = Vw:

Δt = 2D/2Vr - D/2Vr - D/2Vr

Δt = D/Vr - D/Vr = 0

This makes sense because if both move with the same velocity all the time both will do the trip in the same time.

8 0

3 years ago

A Boeing 777 aircraft has a mass of 300,000 kg. At a certain instant during its landing, its speed is 27.0 m/s. If the braking f

GarryVolchara [31]

Answer:

Speed of the airplane 10.0 s later = 12.2 m/s

Explanation:

Mass of Boeing 777 aircraft = 300,000 kg

Braking force = 445,000 N

Deceleration

$a=\frac{445000}{300000}=1.48m/s^2$

Initial velocity, u = 27 m/s

Time , t = 10 s

We have equation of motion, v =u +at

v = 27 + (-1.48) x 10 = 27 - 14.8 = 12.2 m/s

Speed of the airplane 10.0 s later = 12.2 m/s

6 0

3 years ago

What three variable factors determine the force of gravity between any two objects?

brilliants [131]

The force of gravity between two objects is:
F = G*m1*m2/r^2

So, it is dependent of the two masses and the distance between their centers of mass.

5 0

3 years ago

Q1: A cyclist brakes to a stop. His thinking distance was 1m and his braking distance was 3m. What was his overall stopping dist

weeeeeb [17]

Answer:

1.) 4m

2.) 37 m

3.) 62m

4.) 2.5 s

Explanation:

1.) Given that the

Thinking distance = 1m

Breaking distance = 3m

Stopping distance = breaking distance + thinking distance

Stopping distance = 1 + 3 = 4m

2.) Given that the

Stopping distance = 52 m

Thinking distance = 15m

Breaking distance = 52 - 15 = 37m

3.) The stopping distance = 76m

Thinking distance = 14m

Breaking distance = 76 - 14 = 62m

It take the brakes 62m to slow the car down to a stop.

4.) Given that a lorry travels 28m when stopping from a speed of 4m/s. If its braking distance was 18m, what was the driver’s reaction time?

Thinking = stopping distance - braking distance

Thinking distance = 28 - 18 = 10m

Speed = distance/time

4 = 10/reaction time

Reaction time = 10/4

Reaction time = 2.5 s

5.) Question incomplete

5 0

3 years ago