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3 years ago

Identify what happens to the kinetic energy (KE) and gravitational potential energy (PE) of a rock as it falls.

Physics

1 answer:

Oksi-84 [34.3K]3 years ago

3 0

Answer:

KE increases and PE decreases.

Explanation:

POTENTIAL ENERGY (PE):

The potential energy of the rock depends upon the height of the rock, as given by the following formula:

P.E = mgh

Therefore, the potential energy will be highest at the initial point due to the highest height attained by rock. As the rock falls, its height will decrease as a result its potential energy will also decrease.

KINETIC ENERGY (KE):

The kinetic energy of the rock depends upon the velocity of the rock, as given by the following formula:

$K.E = \frac{1}{2}mv^2$

Therefore, the kinetic energy will be zero at the initial point due to the zero velocity of the rock. As the rock falls, its velocity will increase as a result its kinetic energy will also increase.

Hence, the correct option will be:

KE increases and PE decreases.

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1. 5.5 m/s

We can solve the problem by applying the law of conservation of momentum. The total momentum before the collision must be equal to the total momentum after the collision, so we have:

$m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2$

where

m1 = 0.4 kg is the mass of the ball

u1 = 18 m/s is the initial velocity of the ball

m2 = 0.2 kg is the mass of the bottle

u2 = 0 is the initial velocity of the bottle (which is initially at rest)

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v2 = 25 m/s is the final velocity of the bottle

Substituting and re-arranging the equation, we can find the final velocity of the ball:

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$m_1 u_1 + m_2 u_2 = (m_1 +m_2) v$

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m1 = 0.04 kg is the mass of the bullet

u1 = 300 m/s is the initial velocity of the bullet

m2 = 0.5 kg is the mass of the block

u2 = 0 is the initial velocity of the block (which is initially at rest)

v = ? is the final velocity of the bullet+block, which stick and travel together

Substituting and re-arranging the equation, we can find the final velocity of bullet+block:

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3. 6560 N

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$I=\Delta p$ (1)

The impulse can be rewritten as product between force and time of collision:

$I=F \Delta t$

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So, eq.(1) becomes

$F \Delta t = m(v_f -v_i)$

where:

F = ? is the unknown force

$\Delta t = 0.002 s$ is the duration of the impact

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So, by using the equation, we can find the force:

$F=\frac{m (v_f -v_i)}{\Delta t}=\frac{(0.16 kg)(44 m/s-(-38 m/s))}{0.002 s}=6560 N$

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Lady_Fox [76]

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Learn more on gravitational force here;

brainly.com/question/11359658

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