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lawyer [7]
3 years ago
12

A runner starts from rest and in 3 s reaches a speed of 8 m/s. If we assume that the speed changed at a constant rate (constant

net force), what was the average speed during this 3 s interval? average speed = Incorrect: Your answer is incorrect. m/s
Physics
1 answer:
Stells [14]3 years ago
4 0

Answer:

The average speed of the runner is 4 m/s.

Explanation:

Hi there!

The average speed (a.s) is calculated by dividing the traveled distance (d) over the time needed to travel that distance (t):

a.s = d / t

So, let´s find the distance traveled in those 3 s. For that, we can use the equation of position of an object moving in a straight line with constant acceleration:

x = x0 + v0 · t + 1/2 · a · t²

Where:

x = position of the object at time t.

x0 = initial position.

v0 = initial velocity.

t = time.

a = acceleration.

If we place the origin of the frame of reference at the point where the runner starts, then, x0 = 0. Since the runner starts from rest, v0 = 0. So, the equation gets reduced to this:

x = 1/2 · a · t²

We have the time (3 s), so let´s find the acceleration. For that, we can use the equation of velocity of an object moving in a straight line with constant acceleration:

v = v0 + a · t

Where "v" is the velocity at a time "t". Since v0 = 0, then:

v = a · t

At t = 3 s, v = 8 m/s

8 m/s = a · 3 s

8/3 m/s² = a

So let´s find the position of the runner at t = 3 s (In this case, the position of the runner will be equal to the traveled distance):

x = 1/2 · a · t²

x = 1/2 · 8/3 m/s² · (3 s)²

x = 12 m

Now, we can calcualte the average speed:

a.s = d/t

a.s = 12 m / 3 s

a.s = 4 m/s

The average speed of the runner is 4 m/s.

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Read 2 more answers
You've recently read about a chemical laser that generates a 20.0-cm-diameter, 26.0 MW laser beam. One day, after physics class,
aksik [14]

Answer :

(a). The speed of the block is 0.395 m/s.

(b). No

Explanation :

Given that,

Diameter = 20.0 cm

Power = 26.0 MW

Mass = 110 kg

diameter = 20.0 cm

Distance = 100 m

We need to calculate the pressure due to laser

Using formula of pressure

P_{r}=\dfrac{I}{c}

P_{r}=\dfrac{P}{Ac}Put the value into the formula[tex]P_{r}=\dfrac{26.0\times10^{6}}{\pi\times(10\times10^{-2})^2\times3\times10^{8}}

P_{r}=2.75\ N/m^2

We need to calculate the force

Using formula of force

F=P\times A

F=P\times \pi r^2

Put the value into the formula

F=2.75\times\pi (0.01)^2

F=0.086\ N

We need to calculate the acceleration

Using formula of force

F=ma

Put the value into the formula

0.086=110\times a

a=\dfrac{0.086}{110}

a=0.000781\ m/s^2

a=7.81\times10^{-4}\ m/s^2

(a). We need to calculate speed of the block

Using equation of motion

v^2=u^2+2ad

Put the value into the formula

v=\sqrt{2\times7.81\times10^{-4}\times100}

v=0.395\ m/s

(b). No because the velocity is very less.

Hence, (a). The speed of the block is 0.395 m/s.

(b). No

8 0
3 years ago
I WILL MARK BRAINLIEST IF CORRECT!!!
julsineya [31]

0.05*0.2=0.05*0.15+0.015*m2',

m2'=1/6 m/s,

m2'=0.17 m/s

N I C E - D A Y!

6 0
3 years ago
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