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marin [14]
3 years ago
8

A rock dropped from a 20 meter bridge falls into the river below. How long did it take to reach the water? What velocity did it

hit the water with.
Physics
1 answer:
Brut [27]3 years ago
6 0

Answer:

2 s, -20 m/s

Explanation:

Given:

y₀ = 20 m

y = 0 m

v₀ = 0 m/s

a = -9.8 m/s²

Find: t and v

y = y₀ + v₀ t + ½ at²

0 = 20 + 0 + ½ (-9.8) t²

0 = 20 − 4.9 t²

t ≈ 2 s

v² = v₀² + 2a(y − y₀)

v² = 0 + 2(-9.8)(0 − 20)

v ≈ ±20 m/s

Since the rock is falling, v = -20 m/s.

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Two balls of clay, with masses M1 = 0.49 kg and M2 = 0.47 kg, are thrown at each other and stick when they collide. Mass 1 has a
malfutka [58]

Answer:

a) p_i=1.568\hat{i}+0.752 \hat{j}

b) v_{fx}=1.668\ m.s^{-1}

c) v_{fy}=0.7999\ m.s^{-1}

Explanation:

Given masses:

m_1=0.49\ kg

m_2=0.47\ kg

Velocity of mass 1, v_1=3.2 \hat{i}\ m.s^{-1}

Velocity of mass 2, v_2=1.6 \hat{j}\ m.s^{-1}

a)

Initial momentum:

p_i=m_1.v_1+m_2.v_2

p_i=0.49\times 3.2 \hat{i}+0.47\times 1.6 \hat{j}

p_i=1.568\hat{i}+0.752 \hat{j}

b)

magnitude of initial momentum:

p_i=\sqrt{1.568^2+0.752 ^2}

p_i=1.739\ kg.m.s^{-1}

From the conservation of momentum:

p_f=p_i

m_f.v_f=1.739

v_f=\frac{1.739}{0.49+0.47}

v_f=1.85\ m.s^{-1} is the magnitude of final velocity.

Direction of final velocity will be in the direction of momentum:

tan\theta=\frac{0.752 }{1.568}

\theta=25.62^{\circ}

\therefore v_{fx}=1.85\ cos25.62^{\circ}

v_{fx}=1.668\ m.s^{-1}

c)

Vertical component of final velocity:

v_{fy}=1.85\ sin 25.62^{\circ}

v_{fy}=0.7999\ m.s^{-1}

6 0
3 years ago
Which statement is true about an object moving in a circular motion due to centripetal force, F, when the mass is doubled?
marshall27 [118]

Ans) A) Centripetal force will be doubled.

See centripetal force F = mv^2/r

That means centripetal force is directly proportional to the mass of the particle

So, if we double the mass, centripetal force will be increased by twofolds.

So, option A) is correct.

Now, looking at the other options,

B) says centripetal force is unaltered which is incorrect as centripetal force has been altered and increased twofold.

Option C) and D) reduces centripetal force which are also not possible here.

So, only Option A) is correct

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a copper rod is sliding on two conducting rails that make an angle of 18 with respect to each other, as in the drawing. The rod
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Why does a metal spoon left on a bowl of hot soup become warm? A) Metal is a conductor. B) Metal is an insulator. C) Metal produ
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The mcb of rupa's room is tripped and keeps on tripping again and again . if it is a domestic circuit, what could be the reason
kap26 [50]

Overloading

Explanation:

The reason reason why the mcb of rupa's room keeps tripping is due to the fact that excessive current has being supplied to his room.

MCB stands for a miniature circuit breaker.

A miniature circuit breaker opens up the electrical circuit by switching it off when there is overloading or faulty connections.

  • A MCB helps to control the flow of current and it is designed to hand certain limits of electrical voltage.
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learn more:

Circuit brainly.com/question/12472944

#learnwithBrainly

4 0
3 years ago
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