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egoroff_w [7]
3 years ago
6

In the javelin throw at a track-and-field event, the javelin is launched at a speed of 29 m/s at an angle of 36???? above the ho

rizontal. As the javelin travels upward, its velocity points above the horizontal at an angle that decreases as time passes. How much time is required for the angle to be reduced from 36???? at launch to 18?????
Physics
1 answer:
netineya [11]3 years ago
6 0

Answer:

t = 0.96 s  is the time it takes for the angle to reduce

Explanation:

In the launch of projectiles, the velocity is broken down into its x and y components, the velocity in the x-axis is constant, as there is no acceleration, instead the velocity in the axis and is reduced by the effect of the acceleration of gravity.

We can find Vox for the initial conditions

  Voy  = Vo sin θ

  Voy = 29 sin 36

  VoY = 17 m/s

  Vox = Vo cos θ

  Vox = 29 cos 36

  Vox= 23.5 m/s

  Vx = Vox  

The velocity on the x axis is constant

By trigonometry, we find the firing angle

 

  tan θ = Voy/ Vx

  Vy = Vx tan θ

  Vy = 23.5 tan 18

  Vy = 7.64 m/s

Now that we have the vertical speed we can find the time

   Vy = I'm going - g t

   t = (Vy -Voy) / g

   t = (17 - 7.64) /9.8

   t = 0.96 s

Be the time it takes for the angle to reduce

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A car generates 2,552 N and weighs 2,250 pounds. what is the rate of acceleration
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Ans: a = 2.50 m/s^2

Explanation:
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2250 lbs = 1020.583kg

Next use Newton's Second law:
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Where F = 2552N
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An apple is held completely submerged just below the surface of water in a container. The apple is then moved to a deeper point
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Answer:

Explanation:

When the apple is held submerged in water , it experiences a buoyant force due to which it floats in water . One has to apply downward force to keep it submerged. The lower the buoyant force , lower the force needed to submerge it in water.

When apple is held at much deeper point , it experience greater pressure due to column of water around it . So its size or its volume decreases . But its weight remains the same . Due to less volume , buoyant force also decreases ( buoyant force is equal to weight of displaced volume of water. )

Due to buoyant force becoming less , force needed on apple  in downward direction will also be less.

4 0
4 years ago
Inside most ball-point pens is a small spring that compresses as the pen is pressed against the paper. If a force of 0.1 N compr
AnnZ [28]

Answer:

20 N/m

Explanation:

From the question,

The ball-point pen obays hook's law.

From hook's law,

F = ke............................ Equation 1

Where F = Force, k = spring constant, e = compression.

Make k the subject of the equation

k = F/e........................ Equation 2

Given: F = 0.1 N, e = 0.005 m.

Substitute these values into equation 2

k = 0.1/0.005

k = 20 N/m.

Hence the spring constant of the tiny spring is 20 N/m

8 0
3 years ago
A spring with force constant of 59 N/m is compressed by 1.3 cm in a hockey game machine. The compressed spring is used to accele
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Answer:

The puck moves a vertical height of 2.6 cm before stopping

Explanation:

As the puck is accelerated by the spring, the kinetic energy of the puck equals the elastic potential energy of the spring.

So, 1/2mv² = 1/2kx² where m = mass of puck = 39.2 g = 0.0392 g, v = velocity of puck, k = spring constant = 59 N/m and x = compression of spring = 1.3 cm = 0.013 cm.

Now, since the puck has an initial velocity, v before it slides up the inclined surface, its loss in kinetic energy equals its gain in potential energy before it stops. So

1/2mv² = mgh where h = vertical height puck moves and g = acceleration due to gravity = 9.8 m/s².

Substituting the kinetic energy of the puck for the potential energy of the spring, we have

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h = kx²/2mg

= 59 N/m × (0.013 m)²/(0.0392 kg × 9.8 m/s²)

= 0.009971 Nm/0.38416 N

= 0.0259 m

= 2.59 cm

≅ 2.6 cm

So the puck moves a vertical height of 2.6 cm before stopping

3 0
3 years ago
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