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RideAnS [48]
3 years ago
12

9. A child standing on a bus remains still when the bus is at rest. When the bus moves forward and then slows down, the child co

ntinues moving
forward at the original speed. This is an example of
A. Newton's First Law of Motion
B. Newton's Third Law of Motion
C, an action-reaction par
D. Newton's Second Law of Motion
Physics
1 answer:
marin [14]3 years ago
3 0
I think the answer is C
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Which most accurately describes the path that sound​ travels??
emmainna [20.7K]
What are the options ?
6 0
3 years ago
You throw a ball from the balcony onto the court in the basketball arena. You release the ball at a height of 7.00 m above the c
Mariana [72]

Answer:

Your friend has to wait 0.26 s after you throw the ball to start running.

Explanation:

The equation that gives the position vector of the ball is as follows:

r = (x0 + v0 · t · cos α, y0 + v0 · t ·sin α + 1/2 · g · t²)

Where:

x0 = initial horizontal positon

v0 = initial velocity

t = time

α = throwing angle

y0 = initial vertical position

g = acceleration due to gravity

The equation of displacement of your friend is as follows:

x = x0 + v0 · t + 1/2 · a · t²

Where:

x = position of your friend at time t

x0 = initial position

v0 = initial velocity

t = time

a = acceleration

Please, see the attached figure for a description of the situation. Notice that the frame of reference is located at the throwing point.

Let´s find the time of flight of the ball. We know that at the final time, the y-component of the vector r has to be -6.00 m (1 m above the ground). Then:

y = y0 + v0 · t ·sin α + 1/2 · g · t²

-6.00 m = 0 m + 9.00 m/s · t · sin 33.0° - 1/2 · 9.8 m/s² · t²

0 = -4.9 m/s² · t² + 9.00 m/s · sin 33.0° · t + 6.00 m

Solving the quadratic equation:

t = 1.71 s

Now that we have the time of flight, we can calculate the x-component of the vector r (the horizontal distance traveled by the ball):

x= x0 + v0 · t · cos α

x = 0m + 9.00 m/s · 1.71 s · cos 33°

x = 12.9 m

Then, your friend will have to run (12.9 m - 11.0 m) 1.9 m to catch the ball 1 m above the ground.

Let´s see, how much time it takes your friend to run that distance:

x = x0 + v0 · t + 1/2 · a · t²      (x0 = 0, v0 = 0)

x = 1/2 · a · t²

1.9 m = 1/2 · 1.80 m/s² · t²

Solving for t

t = 1.45 s

Then, since the time of flight of the ball is 1.71 s, your friend has to wait

1.71 s - 1.45 s = 0.26 s after you throw the ball to start running.

6 0
3 years ago
Hello please help i’ll give brainliest
Alja [10]

Answer:

First answer.

Explanation:

There may be a 5N force, but if the frictional force also equals 5N, than they cancel eachother out, resulting in the brick still staying still, as it is resting on a (perfectly) level surface, but any amount of force would make the brick move.

4 0
3 years ago
How much energy does the electron have initially in the n=4 excited state?what is the change in energy if the electron from part
Ierofanga [76]
What it looks to be that you found in A was the "initial"...b/c the question asks: 
<span>"how much energy does the electron have 'initially' in the n=4 excited state?" </span>

<span>"final" would be where it 'finally' ends up at, ie. its last stop...as for this question...the 'ground state' as in its lowest energy level. </span>

The answer comes to: <span>−1.36×10^−19 J</span>


You use the same equation for the second part as for part a. 
<span>just have to subract the 2 as in the only diff for part 2 is that you use 1squared rather than 4squared & subract "final -initial" & you should get -2.05*10^-18 as your answer. </span>
8 0
3 years ago
A ball rolls up a hill, going from a speed of 8.09 m/s to a speed of 5.87 m/s in 9.17 seconds. What is its acceleration?
PilotLPTM [1.2K]

Answer:

Explanation:

Comment

It's actually a deceleration. You should get a negative answer because the ball is slowing down.

Givens

vi = 8.09 m/s

vf = 5.87 m/s

t = 9.17

Formula

a = (vf  - vi) /t                     Substitute the givens into the formula

Solution

a = (5.87 - 8.09)/9.17

Answer

a = - 2.22 m/s^2

4 0
1 year ago
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