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2 years ago

The average salinity of sea water is A. 3% B. 3.5% C. 2.5% D. 2%

Physics

2 answers:

mel-nik [20]2 years ago

8 0

The average salinity of seawater is approximately 3.5%, or 35 per thousand.

nadezda [96]2 years ago

7 0

Answer:

In terms of percent, the salinity of most sea water is between 2.5 and 4.5.

Explanation:

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Jennifer and Katie are leaning on each other. Jennifer weighs 150 and Katie weighs 120. Which one is pushing harder on the other

murzikaleks [220]

Jennifer

Explanation:

she has more mass which means she is using more force

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3 years ago

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The equation r (t )=(2t + 4)⋅i + (√ 7 )t⋅ j + 3t ²⋅k the position of a particle in space at time t. Find the angle between the v

velikii [3]

Answer:

$\theta = n\pi/2, {\rm where~n~is~an~integer.}$

Explanation:

We should first find the velocity and acceleration functions. The velocity function is the derivative of the position function with respect to time, and the acceleration function is the derivative of the velocity function with respect to time.

$\vec{v}(t) = \frac{d\vec{r}(t)}{dt} = (2)\^i + (\sqrt{7})\^j + (6t)\^k$

Similarly,

$\vec{a}(t) = \frac{d\vec{v}(t)}{dt} = (6)\^k$

Now, the angle between velocity and acceleration vectors can be found.

The angle between any two vectors can be found by scalar product of them:

$\vec{A}.\vec{B} = |\vec{A}|.|\vec{B}|.\cos(\theta)$

So,

$\vec{v}(t).\vec{a}(t) = |\vec{v}(t)|.|\vec{a}(t)|.\cos(\theta)\\36t = \sqrt{4 + 7 + 36t^2}.6.\cos(\theta)$

At time t = 0, this equation becomes

$0 = 6\sqrt{11}\cos(\theta)\\\cos(\theta) = 0\\\theta = n\pi/2, {\rm where~n~is~an~integer.}$

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2 years ago

according to newton's third law, when a horse pulls on a cart, the cart pulls back on the horse with an equal force on the horse

Debora [2.8K]

Based on Newton's principle, whenever objects A and B interact with each other, they exert forces upon each other.

When a horse pulls on a cart, the horse exerts a force only to the cart. But that force applies only to the cart, not to the horse.

The cart in turn exerts a force on the horse. But that force applies only to the horse, not the cart also.

There are two forces resulting from this interaction - a force on the horse and a force on the cart. The net force on the cart remains as it was --- a positive force in the direction of the horse's movement. Therefore, the cart begins to accelerate and move.

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3 years ago

A ball is thrown straight up. What will

Papessa [141]

Answer:

velocity at the top: 0 m/s

acceleration at the top: -9.8 m/s²

Explanation:

Assuming up is positive and down is negative;

The velocity of the ball at the top of its path will be 0 m/s and the acceleration will be negative.

The velocity is 0 m/s because the ball does not move at the top of its path, and it switches from a positive velocity to a negative velocity. It must go through 0 in order to go from positive to negative.

The acceleration, however, is always negative no matter where the ball is in its motion. This negative acceleration causes the ball to slow down as it reaches the top, and speed up as it reaches the bottom.

Think about it: If there wasn't a negative acceleration, and it was instead 0, the ball would never come back down and instead keep going in a straight line.

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2 years ago

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How is heat converted into work in a steam engine?

Dmitry_Shevchenko [17]

In an extremely simplified explanation,
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