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kupik [55]
3 years ago
7

17. What speed must you toss a ball straight up so it takes 4 s to return to you? Be sure to show all work to support your answe

r.
Physics
1 answer:
Darya [45]3 years ago
3 0

If we tossed up a coin with some velocity then its acceleration in the air is due to gravity which we can take as a = - 9.8 m/s^2

Also it is given that coin returns to initial position after 4 s

So after 4 s its displacement will become ZERO

now in this process we can say that in whole motion of the coin the net displacement of coin is zero and its acceleration is due to gravity remains constant.

We can use kinematics here

\Delta y = v_i t + \frac{1}{2} at^2

0 = v_i (4) - \frac{1}{2}(9.8)(4)^2

v_i = 19.6 m/s

so approximate speed of the coin must be nearly 20 m/s

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A ball on the end of a string is whirled around in a horizontal circle of radius 0.300 m. The plane of the circle is 1.00 m abov
Mamont248 [21]

Answer:

radial acceleration is 41.8 m / s²

Explanation:

The acceleration for circular motion is

     a = v² / r

They also give us the X and Y position where the body falls when the rope breaks, let's write the projectile launch equations

     x = vox t

     y = v₀ₓ t - ½ g t2

Since the circle is horizontally the v₀ₓ is zero (v₀ₓ = 0)

     x = v₀ₓ t

     t = x / v₀ₓ

     y = - ½ g t²

Let's replace and calculate the initial velocity on the X axis

    y = - ½ g (x / vox)²

    v₀ₓ = √ (g x² / 2 y)

    v₀ₓ = √ [- (-9.8) 1.6² / (2 1.00)]

    v₀ₓ = 3.54 m / s

This is the horizontal velocity, but since it circle is in  horizontal position it is also the velocity of the body at the point of rupture.

Now we can calculate the radial acceleration

        a = v² / r

       a = 3.54² / 0.300

       a = 41.8 m / s²

5 0
3 years ago
A gas in a closed container is heated with 10J of energy, causing the lid of the container to rise 2m with 3N of force. What is
AveGali [126]

Explanation:

For this problem, use the first law of thermodynamics. The change in energy equals the increase in heat energy minus the work done.

ΔU=Q−W

We are not given a value for work, but we can solve for it using the force and distance. Work is the product of force and displacement.

W=FΔx

W=3N×2m

W=6J

Now that we have the value of work done and the value for heat added, we can solve for the total change in energy.

ΔU=Q−W

ΔU=10J−6J

ΔU=4J

Answer is 4J

i think this may help you very much

3 0
2 years ago
What is the kinetic energy of a 10kg object that is moving with a speed of 60m/s.
Sergio039 [100]

The answer is 18000 J

I hope this helps!^^ , if you need the work to be shown please tell me, I hope you have a great day!^^

5 0
2 years ago
A field measuring 12 meters by 16 meters is to have a brick paver walkway installed all around it, increasing the total area to
kolezko [41]

Answer:

1.5 m

Explanation:

Length. L = 12 m

Width, W = 16 m

Area, A = 12 x 16 = 192 m^2

Let the width of pavement be d.

The new length, L' = 12 + 2d

the new width, W' = 16 + 2d  

New Area, A' = L' x W' = (12 + 2d)(16 + 2d) = 192 + 56 d + 4d^2

Difference in area = A' - A

285 =  192 + 56 d + 4d^2 - 192

93 =  56 d + 4d^2

4d^2 + 56 d - 93 = 0

d = \frac{-56\pm \sqrt{56^{2}+4\times 4\times 93}}{8}

d=\frac{-56\pm 87.72}{8}\

d = 1.5 m

Thus, the width of the pavement is 1.5 m.

6 0
3 years ago
A van is traveling with an initial velocity of 12 m/s. The driver takes a time of 45 seconds to speed up to a velocity of 20 m/s
Rufina [12.5K]
  • Initial velocity=u=12m/s
  • Final velocity=v=20m/s
  • Time=t=45s

\\ \rm\hookrightarrow Acceleration=\dfrac{v-u}{t}

\\ \rm\hookrightarrow Acceleration=\dfrac{20-12}{45}

\\ \rm\hookrightarrow Acceleration=\dfrac{8}{45}

\\ \rm\hookrightarrow Acceleration=0.1m/s^2

Now

  • Distance=s

\\ \rm\hookrightarrow v^2-u^2=2as

\\ \rm\hookrightarrow (20)^2-12^2=2(0.1)s

\\ \rm\hookrightarrow 400-144=0.2s

\\ \rm\hookrightarrow 256=0.2s

\\ \rm\hookrightarrow s=\dfrac{256}{0.2}

\\ \rm\hookrightarrow s=1280m

4 0
3 years ago
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