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Fittoniya [83]
3 years ago
6

A watermelon is dropped from the top of a 80m tall building. We want to find the velocity of the watermelon after it falls for 1

.35s. We can ignore air resistance.
Kinematics formula would be most helpful to solve for the target unknown?

Answer choices in picture.

Physics
1 answer:
White raven [17]3 years ago
7 0

Answer:

v_f = v_i + at

v_f = 13.23 m/s

Explanation:

Height Of the watermelon when it is dropped is given as

h = 80 m

time of fall under gravity

t = 1.35 s

now if water melon start from rest then we have

v_i = 0

acceleration due to gravity for watermelon

a = 9.81 m/s^2

now we need to find the final speed of watermelon

v_f = v_i + at

so we will have

v_f = 0 + (9.81)(1.35)

v_f = 13.23 m/s

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a toy propeller fan with a moment of inertia of .034 kg x m^2 has a net torque of .11Nxm applied to it. what angular acceleratio
Harman [31]

Answer:

The  angular acceleration is  \alpha  = 3.235 \ rad/s ^2

Explanation:

From the question we are told that

    The moment of inertia is  I  =  0.034\ kg \cdot m^2

     The  net torque is  \tau  =  0.11\ N \cdot m

Generally the net torque is mathematically represented as

           \tau =  I  *  \alpha

Where \alpha is the angular acceleration so  

        \alpha  =  \frac{\tau }{I}

substituting values

         \alpha  =  \frac{0.1 1}{ 0.034}

        \alpha  = 3.235 \ rad/s ^2

6 0
3 years ago
1. What coefficients would balance the following equation?
maksim [4K]

Answer:

D. 4Al + 3O2 → 2Al2O3

Explanation:

Chemical reactions involves the chemical combination of two or more substances called REACTANTS to yield other substances called PRODUCTS. However, in accordance with the LAW OF CONSERVATION OF MASS, the amount of reactants must be equal to that of the products.

To accomplish this, the reaction must be BALANCED. A balanced equation is an equation in which the number of atoms of each element in the reactant side equals the number of atoms in the product side. In this reaction involving Aluminum and Oxygen to give Aluminum oxide as follows:

Al + 02 → Al2O3

A coefficient is used to balance the number of atoms on both sides of the equation as follows:

4Al + 3O2 → 2Al2O3

3 0
3 years ago
Read 2 more answers
The Moon orbits Earth in an average of p = 27.3 days at an average distance of a =384,000 kilometers. Using Newton’s version of
Korvikt [17]

Answer:

The mass of the earth, M=6.023\times 10^{24}\ kg

Explanation:

It is given that,

Time taken by the moon to orbit the earth, T=27.3\ days=2358720\ m

Distance between moon and the earth,r=384000\ km=384\times 10^6\ m

We need to find the mass of the Earth using Kepler's third law of motion as :

T^2=\dfrac{4\pi^2}{GM}r^3

M=\dfrac{4\pi^2r^3}{T^2G}

M=\dfrac{4\pi^2\times (384\times 10^6)^3}{(2358720)^2\times 6.67\times 10^{-11}}

M=6.023\times 10^{24}\ kg

So, the mass of the earth is 6.023\times 10^{24}\ kg. Hence, this is the required solution.

7 0
3 years ago
Describe how the mass, luminosity, surface temperature, and radius of main-sequence stars change in value going from the “bottom
Sladkaya [172]

Answer:

1. Least massive stars are the coolest and least luminous, lower right of main sequence, on HR diagram.  

2. Most massive are the hottest and most luminous, upper left of main sequence on Hr Diagram.  

3. The radius of stars are related to their sprectral type. having the O being the hottest upper left and M being the coolest bottom right.

4 0
3 years ago
A dolphin in an aquatic show jumps straight up out of the water at a velocity of 15.0 m/s. (a) List the knowns in this problem.
astra-53 [7]

Answer:

a)

Y0 = 0 m

Vy0 = 15 m/s

ay = -9.81 m/s^2

b) 7.71 m

c) 3.06 s

Explanation:

The knowns are that the initial vertical speed (at t = 0 s) is 15 m/s upwards. Also at that time the dolphin is coming out of the water, so its initial position is 0 m. And since we can safely assume this happens in Earth, the acceleration is the acceleration of gravity, which is 9.81 m/s^2 pointing downwards

Y(0) = 0 m

Vy(0) = 15 m/s

ay = -9.81 m/s^2 (negative because it points down)

Since acceleration is constant we can use the equation for uniformly accelerated movement:

Y(t) = Y0 + Vy0 * t + 1/2 * a * t^2

To find the highest point we do the first time derivative (this is the speed:

V(t) = Vy0 + a * t

We equate this to zero

0 = Vy0 + a * t

0 = 15 - 9.81 * t

15 = 9.81 * t

t = 0.654 s

At this time it will have a height of:

Y(0.654) = 0 + 15 * 0.654 - 1/2 * 9.81 * 0.654^2 = 7.71 m

The doplhin jumps and falls back into the water, when it falls again it position will be 0 again. So we can equate the position to zero to find how long it was in the air knowing that it started the jump at t = 0s.

0 = Y0 + Vy0 * t + 1/2 * a * t^2

0 = 0 + 15 * t - 1/2 * 9.81 t^2

0 = 15 * t - 4.9 * t^2

0 = t * (15 - 4.9 * t)

t1 = 0 This is the moment it jumped into the air

0 = 15 - 4.9 * t2

15 = 4.9 * t2

t2 = 3.06 s This is the moment when it falls again.

3.06 - 0 = 3.06 s

5 0
3 years ago
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