A ball is thrown upward at a velocity of 20m/s. What is the velocity after 3 seconds?

Answers

Answer 1

Answer:
This is a perfect problem to use positive and negative velocities.

Let's call the positive direction the direction that points UP.
Then the negative direction is the one that points down.

The acceleration of gravity on Earth is 9.8 m/s² down. That means
that any object with no forces on it except gravity gains 9.8 m/s of
speed downward every second.

OK. Ready to go to work:

The ball's initial velocity is +(up)20.0 m/s .
Every second after the toss, the ball has -(down)9.8 m/s more velocity.

The ball's velocity after 3 seconds is

+20 + 3(-9.8) =

20 - 29.4 = - 9.4 m/s .

That means it's velocity at that time is 9.4 m/s pointing down.

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Height of cannon 5 m, initial speed of projectile 15m/s, angle of launch 0 degrees. What is the range and time in the air? Please show work!

Answers

Answer:

The range is 15.15 m and the time in the air is 1.01 s

Explanation:

Horizontal Motion

When an object is thrown horizontally (with angle 0°) with a speed v from a height h, it follows a curved path ruled exclusively by gravity until it eventually hits the ground.

The range or maximum horizontal distance traveled by the object can be calculated as follows:

$\displaystyle d=v\cdot\sqrt{\frac {2h}{g}}$

To calculate the time the object takes to hit the ground, we use the equation below:

$\displaystyle t=\sqrt{(2h)/(g)}$

The cannon is shot from a height of h=5 m with an initial speed of v=15 m/s. The range is calculated below:

$\displaystyle d=15\cdot\sqrt{\frac {2*5}{9.8}}=15*1.01$

d = 15.15 m

The time in the air is:

$\displaystyle t=\sqrt{(2*5)/(9.8)}$

t = 1.01 s

The range is 15.15 m and the time in the air is 1.01 s

Evidence gathered from publicly observable behavior is known as _________ evidence.

Answers

Empirical because it is what you need to know the source of knowledge gather by observation or experimentation.

Describe a situation when you might travel at a high velocity but a low acceleration

Answers

Relaxing in a comfortable seat, reading a book and listening to
some mp3 stored on your pod or your pad, your eyes are getting
heavy, you adjust yourself slightly in the seat, getting slightly more
comfortable, your eyes get so heavy that you can't hold them open,
and you doze off.

Your seat is #24-B in a passenger jet in straight and level flight,
cruising in calm air 35,000 feet above the ground, taking you to
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A skateboarder has an acceleration of -1.9 m/s2. If her initial speed is 6 m/s how long does it take her to stop?A. 4.1s
B. 3.2s
C. 0.32s
D. 2.1s

Answers

intial speed = 6m/s
final speed = 0 m/s as it stop
acceleration = 1.9 m/s2
time taken = t s

v=u+at
0=6+1.9*t
t=3.15 s = 3.2 s

Is it possible for a population with a high birth rate to decrease in size.

Answers

Sure, if the mortality (death) rate is even higher than the birth rate.

A car travels at a steady speed of 10 m/s. What distance is covered in a minute?

Answers

Answer:

600

Explanation:

10*60=600

You multiply it by 60 because it is saying that it travels 1 mile per second and there are 60 seconds in one minute.

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