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hjlf
3 years ago
14

A rock is thrown horizontally off a cliff with an initial velocity of 15 m/s. How high was the cliff if the rock lands 22 m from

the base of the cliff?
Physics
2 answers:
Helen [10]3 years ago
3 0

Answer:

22 m

Explanation:

Hunter-Best [27]3 years ago
3 0

Answer:

cliff height = 10.55 m

Explanation:

Remarks

  • This is one of those questions that defies belief. The final vertical velocity is the same as if you just dropped the rock, which is amazing.
  • Another amazing fact is that the horizontal speed has no acceleration.
  • And  amazing fact number three is the the vertical initial speed is 0.
  • And finally, the time taken to go horizontally = time to go vertically.

Solution

<u>Time</u>

So the time taken is d = r * t  

Remember, this formula can only be used when there is no acceleration.

d = 22 meters

r = 15 m/s

t = ?

t = d / r

t = 22 / 15

t = 1.467

<u>Height of the Cliff</u>

vi = 0 (vertially)

a = 9.8 m/s^2

t = 1.467 seconds    The time horizontally and vertically is the same.

d = ?

<u>Formula</u>

d = vi*t + 1/2 a t^2

<u>Solution</u>

d = 0 + 1/2 * 9.8 * 1.467^2

d = 10.55 meters.

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Answer:

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<u>Question 1</u>

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Equating the new formula of pressure to the formula used in question 1 above

P=0.5v^{2}\rho=hg\rho

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v^{2}=2hg

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v=\sqrt 2*10*6.4=11.3137085  m/s

Rounding off to 1 decimal place

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<u>Question 3</u>

As already illustrated

v=\sqrt 2hg

Taking g as 9.8 and h now is 8m

v=\sqrt 2*8*9.8

v=12.52198067

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A 0.453 kg pendulum bob passes through the lowest part of its path at a speed of 2.58 m/s. What is the tension in the pendulum c
harkovskaia [24]

Answer with Explanation:

Mass of pendulum bob, m=0.453 kg

Speed, v_1=2.58 m/s

a.r=75.1 cm=75.1\times 10^{-2}m=0.751 m

1cm=10^{-2} m

Tension in the pendulum cable is given  by

Tension=Centripetal force+force due to gravity

T=\frac{mv^2}{r}+mg

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gh_1+\frac{1}{2}v^2_1=gh_2+\frac{1}{2}v^2_2

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\theta=cos^{-1}(0.55)=56.6^{\circ}

c.When the pendulum reaches at highest point then

Acceleration, a=0

Therefore, the tension  in the pendulum cable

T=mgcos\theta

Substitute the values

T=0.453\times 9.8cos56.6

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