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4 years ago

14

A physics book slides off a horizontal table top with a speed of 1.10m/s. It strikes the floor after a time of 0.400s. Find the

height of the table top above the floor.

1 answer:

Andreas93 [3]4 years ago

6 0

S = V1t +1/2 gt2 = 0*0.400 + 1/2 * 9.8 * 0.400^2
S = 0 + 0.784 = 0.78 m = nearly 0.8m

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Which statement best describes how atoms differ from molecules?

choli [55]

<u>Answer</u>:

None of the given options are correct.

<u>Explanation</u>:

As we all know, molecules can be broken down into atoms, and atoms can be broken down into smaller elements, which are electrons, neutrons, and protons.

Atoms forms bonds together to form molecules, and molecules form bonds together to form higher complex elements.

Moreover, molecules consists of different atoms. Considering options, let us first look whether the statements are correct or not, and then will look upon similarity. A is true, as explained above, B is false, as if atoms stopped making bonds, nothing, not even earth would exist. C is definitely false, And even D is false. Considering difference, the correct option is none of the given.

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A rock is thrown off a 50.0 m high cliff. How fast must the rock leave the cliff top to land on level ground below, 90 m from th

blagie [28]

Answer:

The rock must leave the cliff at a velocity of 28.2 m/s

Explanation:

The position vector of the rock at a time t can be calculated using the following equation:

r = (x0 + v0x · t, y0 + 1/2 · g · t²)

Where:

r = position vector at time t.

x0 = initial horizontal position.

v0x = initial horizontal velocity.

t = time.

g = acceleration due to gravity (-9.81 m/s² considering the upward direction as positive).

Please, see the attached figure for a graphical description of the problem. Notice that the origin of the frame of reference is located at the edge of the cliff so that x0 and y0 = 0.

When the rock reaches the ground, the position vector will be (see r1 in the figure):

r1 = (90 m, -50 m)

Then, using the equation of the vector position written above:

90 m = x0 + v0x · t

-50 m = y0 + 1/2 · g · t²

Since x0 and y0 = 0:

90 m = v0x · t

-50 m = 1/2 · g · t²

Let´s use the equation of the y-component of the vector r1 to find the time it takes the rock to reach the ground and with that time we can calculate v0x:

-50 m = 1/2 · g · t²

-50 m = -1/2 · 9.81 m/s² · t²

-50 m / -1/2 · 9.81 m/s² = t²

t = 3.19 s

Now, using the equation of the x-component of r1:

90 m = v0x · t

90 m = v0x · 3.19 s

v0x = 90 m / 3.19 s

v0x = 28.2 m/s

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3 years ago

Which climate does Western California have

maxonik [38]

Answer:

Along the western side of the Coast Range the climate is dominated by the Pacific Ocean. Warm winters, cool summers, small daily and seasonal temperature ranges, and high relative humidities are characteristic of this area.

Explanation:

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4 years ago

Which of the elements below have seven electrons in their outermost energy levels? A.) Cr, Mn, and Fe B.) Br, I, and Ci C.) O, S

Andrei [34K]

Answer:

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3 years ago

a runner moves 2.88 m/s north. she accelerates at 0.350 m/s2 at -52.0 angle. at the point where she is running directly east, wh

Naily [24]

Answer:

11.7 m

Explanation:

I assume north is the y direction and x is the east direction, so Δx refers to the displacement in the east direction.

First, find the time it takes for the velocity to change from directly north to directly east.

Given (in the y direction):

v₀ = 2.88 m/s

v = 0 m/s

a = 0.350 m/s² sin(-52.0°) = -0.276 m/s²

Find: t

v = at + v₀

(0 m/s) = (-0.276 m/s²) t + (2.88 m/s)

t = 10.4 s

Given (in the x direction):

v₀ = 0 m/s

a = 0.350 m/s² cos(-52.0°) = 0.215 m/s²

t = 10.4 s

Find: Δx

Δx = v₀ t + ½ at²

Δx = (0 m/s) (10.4 s) + ½ (0.215 m/s²) (10.4 s)²

Δx = 11.7 m

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3 years ago