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3 years ago

Which number is right

Physics

1 answer:

KatRina [158]3 years ago

7 0

'C' is the correct choice. Please, do me a favor ... take a few minutes to read the other choices, A, B and D, and understand what's wrong with each of those. That's MUCH MUCH more important than knowing that C is correct.

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Corey runs a 100-meter race. 7 seconds after the race started Corey is 45 meters from the starting line and reaches his max spee

RUDIKE [14]

Answer:

Corey's max speed is $7 \frac{m}{s}$
the distance Corey's covers in z seconds is $7 \frac{m}{s} * z \ s$
$d (z) = 45 m + 7 \frac{m}{s} * z$
$d (x) = 45 m + 7 \frac{m}{s} * (x-7 s)$

Explanation:

<h3>Corey's max speed</h3>

For constant speed, we know:

$v=\frac{distance}{time}$

The distance between the 80 meters and the 45 meters is:

$distance = 80 m - 45 m = 35 m$

and the time it took to reach the 80 meter will be:

$time = 12 s - 7 s = 5 s$

So, Corey's max speed is

$v_{max}=\frac{35 m}{5 s} = 7 \frac{m}{s}$

<h3>How far runs Corey</h3>

As the velocity of Corey's is $v_{max}$ , the distance Corey's covers in z seconds is

$distance = v_{max} * z \ s$

$distance = 7 \frac{m}{s} * z \ s$

<h3>What is Corey's distance from the starting line</h3>

At time 7 + z seconds the distance will be the 45 meters he covers in the first part of the race plus the distance he traveled at constant speed. this is:

$d (z) = 45 m + v_{max} * z$

$d (z) = 45 m +7 \frac{m}{s} * z$

At time x ( x greater or equal to 7 seconds) the distance will be the 45 meters he covers in the first part of the race plus the distance he traveled at constant speed. this is:

$d (x) = 45 m + v_{max} * (x-7 s)$

$d (x) = 45 m + 7 \frac{m}{s} * (x-7 s)$

4 0

3 years ago

Write any two important of gravitational force?

eimsori [14]

Answer:

Explanation:

Gravitational force is important because:

1. because of the gravitational force of the earth, the atmosphere is present around its surface, which is crucial for sustainability of life on earth

2. we are able to perform motion due to the force of gravity

5 0

3 years ago

Microwave ovens have a plate that rotates at a rate of about 7.0 rev/min. What is this in revolutions per second?

Lera25 [3.4K]

Answer:

The value is $w = 0.1167 \ rev/second$

Explanation:

From the question we are told that

The rate at which the plate rotates is $w =7.0 \ rev/min$

Generally the revolution per second is mathematically represented as

$w = \frac{7.0}{60}$

=> $w = 0.1167 \ rev/second$

5 0

3 years ago

While traveling along a highway a driver slows from 31 m/s to 15 m/s in 8 seconds. What is the automobile’s acceleration? (Remem

MaRussiya [10]

Answer:

The automobile's acceleration in that time interval is -2 m/s^2

Explanation:

The acceleration is defined as the rate of change of the velocity.

The average acceleration in a given lapse of time is calculated as:

A = (final velocity - initial velocity)/time.

In this case, we have:

initial velocity = 31 m/s

final velocity = 15 m/s

time = 8 seconds.

Then the average acceleration is:

A = (15m/s - 31m/s)/8s = -2 m/s^2

8 0

2 years ago

A shot is fired at an angle of 60 degree horizontal with Kinetic energy E. If air resistance is ignored, the K.E at the top of t

Lapatulllka [165]

I'm not sure what "60 degree horizontal" means.

I'm going to assume that it means a direction aimed 60 degrees
above the horizon and 30 degrees below the zenith.

Now, I'll answer the question that I have invented.

When the shot is fired with speed of 'S' in that direction,
the horizontal component of its velocity is S cos(60) = 0.5 S ,
and the vertical component is S sin(60) = S√3/2 = 0.866 S . (rounded)

-- 0.75 of its kinetic energy is due to its vertical velocity.
That much of its KE gets used up by climbing against gravity.

-- 0.25 of its kinetic energy is due to its horizontal velocity.
That doesn't change.

-- So at the top of its trajectory, its KE is 0.25 of what it had originally.

That's E/4 .

3 0

3 years ago