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3 years ago

13

The Celsius tempersture scale is based on which of the following? a) vapor b) the human body c) the boiling point of air d) the

boiling and freezing points of water

2 answers:

Darina [25.2K]3 years ago

8 0

I think d is the correct answer

tatuchka [14]3 years ago

8 0

I believe the answer is D because the freezing point for water is 0, and the boiling point is 100 in the Celsius scale, so D makes the most sense

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Why would elements found in the same group on the periodic table have similar reactivity’s

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Answer:

D. They have the same number of valence electrons

Explanation:

In order to answer this question we need to understand the following.

Valence electrons refers to the outermost electron(s) in the outermost energy level of an atom.
Elements in the same group in the periodic table have the same number of valence electrons. For instance, group 2A elements have 2 valence electrons.
The reactivity of elements in the periodic table is based on the number of valence electrons and the ease of gaining or losing electrons.
Elements in the same group have similar valence electrons and therefore share similar chemical properties such as reactivity.
Hence, elements in the same group have same number of valence electron and will thus have similar reactivity.

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4 years ago

When a baseball hits a

frez [133]

The reaction force is the glove pushing against the ball because the reaction force would be the ball pushing onto the glove.

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3 0

3 years ago

What type of bone is the thigh

LUCKY_DIMON [66]

Answer:

hich graph represents this system?

y = 2 x + 1. y = negative 4 x + 7.

On a coordinate plane, a line goes through (0, 7) and (1, 3) and another goes through (1, 3) and (2, 5).

On a coordinate plane, a line goes through (negative 4, 0) and (0, 7) and another line goes through (negative 4, 3) and (0, 1).

On a coordinate plane, a line goes through (0, negative 4) and (1, 3) and another goes through (0, 2) and (1, 3).

On a coordinate plane, a line goes through (0, 7) and (8, 5) and another line goes through (0, 1) and (8, 5).

Explanation:

asdfgh

4 0

3 years ago

Read 2 more answers

A rock is thrown off a cliff at an angle of 53° with respect to the horizontal. The cliff is 100 m high. The initial speed of th

Nadusha1986 [10]

(a) 129.3 m

The motion of the rock is a projectile motion, consisting of two indipendent motions along the x- direction and the y-direction. In particular, the motion along the x- (horizontal) direction is a uniform motion with constant speed, while the motion along the y- (vertical) direction is an accelerated motion with constant acceleration $g=-9.8 m/s^2$ downward.

The maximum height of the rock is reached when the vertical component of the velocity becomes zero. The vertical velocity at time t is given by

$v(t) = v_0 sin \theta +gt$

where

$v_0 = 30 m/s$ is the initial velocity of the rock

$\theta=53^{\circ}$ is the angle

t is the time

Requiring $v(t)=0$ , we find the time at which the heigth is maximum:

$0=v_0 sin \theta + gt\\t=\frac{-v_0 sin \theta}{g}=-\frac{(30)(sin 53^{\circ})}{(-9.8)}=2.44 s$

The heigth of the rock at time t is given by

$y(t) = h+(v_0 sin\theta) t + \frac{1}{2}gt^2$

Where h=100 m is the initial heigth. Substituting t = 2.44 s, we find the maximum height of the rock:

$y=100+(30)(sin 53^{\circ})(2.44)+\frac{1}{2}(-9.8)(2.44)^2=129.3 m$

(b) 44.1 m

For this part of the problem, we just need to consider the horizontal motion of the rock. The horizontal displacement of the rock at time t is given by

$x(t) = (v_0 cos \theta) t$

where

$v_0 cos \theta$ is the horizontal component of the velocity, which remains constant during the entire motion

t is the time

If we substitute

t = 2.44 s

Which is the time at which the rock reaches the maximum height, we find how far the rock has moved at that time:

$x=(30)(cos 53^{\circ})(2.44)=44.1 m$

(c) 7.58 s

For this part, we need to consider the vertical motion again.

We said that the vertical position of the rock at time t is

$y(t) = h+(v_0 sin\theta) t + \frac{1}{2}gt^2$

By substituting

y(t)=0

We find the time t at which the rock reaches the heigth y=0, so the time at which the rock reaches the ground:

$0=100+(30)(sin 53^{\circ})t+\frac{1}{2}(-9.8)t^2\\0=100+23.96t-4.9t^2$

which gives two solutions:

t = -2.69 s (negative, we discard it)

t = 7.58 s --> this is our solution

(d) 136.8 m

The range of the rock can be simply calculated by calculating the horizontal distance travelled by the rock when it reaches the ground, so when

t = 7.58 s

Since the horizontal position of the rock is given by

$x(t) = (v_0 cos \theta) t$

Substituting

$v_0 = 30 m/s\\\theta=53^{\circ}$

and t = 7.58 s we find:

$x=(30)(cos 53^{\circ})(7.58)=136.8 m$

(e) (36.1 m, 128.3 m), (72.2 m, 117.4 m), (108.3 m, 67.4 m)

Using the equations of motions along the two directions:

$x(t) = (v_0 cos \theta) t$

$y(t) = h+(v_0 sin\theta) t + \frac{1}{2}gt^2$

And substituting the different times, we find:

$x(2.0 s)=(30)(cos 53^{\circ})(2.0)=36.1 m$

$y(2.0 s)= 100+(23.96)(2.0)-4.9(2.0)^2=128.3 m$

$x(4.0 s)=(30)(cos 53^{\circ})(4.0)=72.2 m$

$y(4.0 s)= 100+(23.96)(4.0)-4.9(4.0)^2=117.4 m$

$x(6.0 s)=(30)(cos 53^{\circ})(6.0)=108.3 m$

$y(6.0 s)= 100+(23.96)(6.0)-4.9(6.0)^2=67.4 m$

3 0

3 years ago

Need help, marking brainliest:)

katrin2010 [14]

Answer:

Always

Explanation:

Unbalanced forces means an acceleration, meaning a change in speed!

5 0

3 years ago