Question 4

Vitek1552 [10]

an input device is (a piece of computer hardware equipment) used to provide data and control signals to an information processing system such as acomputer or information appliance.

5 0

3 years ago

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A 58.0-kg projectile is fired at an angle of 30.0° above the horizontal with an initial speed of 140 m/s from the top of a cliff

strojnjashka [21]

(a) $6.43\cdot 10^5 J$

The total mechanical energy of the projectile at the beginning is the sum of the initial kinetic energy (K) and potential energy (U):

$E=K+U$

The initial kinetic energy is:

$K=\frac{1}{2}mv^2$

where m = 58.0 kg is the mass of the projectile and $v=140 m/s$ is the initial speed. Substituting,

$K=\frac{1}{2}(58 kg)(140 m/s)^2=5.68\cdot 10^5 J$

The initial potential energy is given by

$U=mgh$

where g=9.8 m/s^2 is the gravitational acceleration and h=132 m is the height of the cliff. Substituting,

$U=(58.0 kg)(9.8 m/s^2)(132 m)=7.5\cdot 10^4 J$

So, the initial mechanical energy is

$E=K+U=5.68\cdot 10^5 J+7.5\cdot 10^4 J=6.43\cdot 10^5 J$

(b) $-1.67 \cdot 10^5 J$

We need to calculate the total mechanical energy of the projectile when it reaches its maximum height of y=336 m, where it is travelling at a speed of v=99.2 m/s.

The kinetic energy is

$K=\frac{1}{2}(58 kg)(99.2 m/s)^2=2.85\cdot 10^5 J$

while the potential energy is

$U=(58.0 kg)(9.8 m/s^2)(336 m)=1.91\cdot 10^5 J$

So, the mechanical energy is

$E=K+U=2.85\cdot 10^5 J+1.91 \cdot 10^5 J=4.76\cdot 10^5 J$

And the work done by friction is equal to the difference between the initial mechanical energy of the projectile, and the new mechanical energy:

$W=E_f-E_i=4.76\cdot 10^5 J-6.43\cdot 10^5 J=-1.67 \cdot 10^5 J$

And the work is negative because air friction is opposite to the direction of motion of the projectile.

(c) 88.1 m/s

The work done by air friction when the projectile goes down is one and a half times (which means 1.5 times) the work done when it is going up, so:

$W=(1.5)(-1.67\cdot 10^5 J)=-2.51\cdot 10^5 J$

When the projectile hits the ground, its potential energy is zero, because the heigth is zero: h=0, U=0. So, the projectile has only kinetic energy:

E = K

The final mechanical energy of the projectile will be the mechanical energy at the point of maximum height plus the work done by friction:

$E_f = E_h + W=4.76\cdot 10^5 J +(-2.51\cdot 10^5 J)=2.25\cdot 10^5 J$

And this is only kinetic energy:

$E=K=\frac{1}{2}mv^2$

So, we can solve to find the final speed:

$v=\sqrt{\frac{2E}{m}}=\sqrt{\frac{2(2.25\cdot 10^5 J)}{58 kg}}=88.1 m/s$

4 0

3 years ago

DUE IN 15 MIN!

Fiesta28 [93]

Answer:

Law of multiple proportions

8 0

2 years ago

How safe is Hydroelectric Energy? Use in your own words.

pickupchik [31]

This is your perfect answer
It is flexible. Water flow can be adjusted and even conserved according to the need for power. It is safe! Compared with the use of fossil fuels and nuclear energy, hydropower is a much safer system..

4 0

2 years ago

Suppose a ceiling fan has a mass of 7.5 kg and is 9.7 m above the ground. What is the gravitational potential energy of the ceil

EleoNora [17]

The gravitational potential energy (G.P.E) of the ceiling fan is 712.95 Joules.

Given the following data:

Mass of ceiling fan = 7.5 kg

Height = 0.7 m

Scientific data:

Acceleration due to gravity = 9.8 $m/s^2$

To calculate the gravitational potential energy (G.P.E) of the ceiling fan:

<h3>What is gravitational potential energy?</h3>

Gravitational potential energy (G.P.E) can be defined as the energy that is possessed by an object or body due to its position (height) above planet Earth.

Mathematically, gravitational potential energy (G.P.E) is given by this formula;

$GPE = mgh$

Where:

G.P.E is the gravitational potential energy.

m is the mass of an object.

g is the acceleration due to gravity.

h is the height of an object.

Substituting the given parameters into the formula, we have;

$GPE = 7.5 \times 9.8 \times 9.7$

GPE = 712.95 Joules.

Read more on potential energy here: brainly.com/question/8664733

8 0

2 years ago