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3 years ago

7

Why are unit of length mass and time independent with each other?

1 answer:

mariarad [96]3 years ago

4 0

Масса (килограмм), длина (метр) и время (секунда) - это 3 из 7 основных единиц в системе СИ.

Базовые единицы произвольно определены как то, что они есть, поэтому они не могут быть получены.

Все другие единицы в системе СИ являются производными от 7 основных единиц, таких как скорость (метр / секунда).

Остальные 4 - это температура (Кельвин), количество вещества (моль), электрический ток (ампер) и светимость (кандела).

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Joe balances a stationary coin on the the tip of his finger 20 cm from the top of the table. How much work is Joe doing?

adell [148]

The work done by Joe is 0 J.

<u>Explanation</u>:

When a force is applied to an object, there will be a movement because of the applied force to a certain distance. This transfer of energy when a force is applied to an object that tends to move the object is known as work done.

The energy is transferred from one state to another and the stored energy is equal to the work done.

W = F . D

where F represents the force in newton,

D represents the distance or displacement of an object.

Force = 0 N, D = 20 cm = 0.20 m

W = 0 $\times$ 0.20 = 0 J.

Hence the work done by Joe is 0 J.

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3 years ago

Under which type of change would more organisms be able to survive? Why?

topjm [15]

The adaptation that is genetic change or mutatiton help makes an organism to survive better in their new environment.

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3 years ago

(a) Calculate the force (in N) needed to bring a 1100 kg car to rest from a speed of 85.0 km/h in a distance of 125 m (a fairly

nasty-shy [4]

(a) -2451 N

We can start by calculating the acceleration of the car. We have:

$u=85.0 km/h = 23.6 m/s$ is the initial velocity

v = 0 is the final velocity of the car

d = 125 m is the stopping distance

So we can use the following equation

$v^2 - u^2 = 2ad$

To find the acceleration of the car, a:

$a=\frac{v^2-u^2}{2d}=\frac{0-(23.6 m/s)^2}{2(125 m)}=-2.23 m/s^2$

Now we can use Newton's second Law:

F = ma

where m = 1100 kg to find the force exerted on the car in order to stop it; we find:

$F=(1100 kg)(-2.23 m/s^2)=-2451 N$

and the negative sign means the force is in the opposite direction to the motion of the car.

(b) $-1.53\cdot 10^5 N$

We can use again the equation

$v^2 - u^2 = 2ad$

To find the acceleration of the car. This time we have

$u=85.0 km/h = 23.6 m/s$ is the initial velocity

v = 0 is the final velocity of the car

d = 2.0 m is the stopping distance

Substituting and solving for a,

$a=\frac{v^2-u^2}{2d}=\frac{0-(23.6 m/s)^2}{2(2 m)}=-139.2 m/s^2$

So now we can find the force exerted on the car by using again Newton's second law:

$F=ma=(1100 kg)(-139.2 m/s^2)=-1.53\cdot 10^5 N$

As we can see, the force is much stronger than the force exerted in part a).

8 0

3 years ago

Which of the following changes would be a physical change to a substance?(1 point)

Naddika [18.5K]

Answer:

all of them I think

Explanation:

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2 years ago

What is time write its SI unit

lisabon 2012 [21]

The SI unit of time is second

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3 years ago