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3 years ago

C

Physics

1 answer:

AlexFokin [52]3 years ago

7 0

Answer:

27J

3528J

Explanation:

First problem:

Given parameters:

Mass of tennis ball = 0.06kg

Velocity of tennis ball = 30m/s

Unknown:

Kinetic energy = ?

Solution:

Kinetic energy is the energy due to the motion of a body.

It is expressed as:

K.E = $\frac{1}{2}$ m v²

K.E = $\frac{1}{2}$ x 0.06 x 30² = 27J

Second problem:

Given parameters:

Mass = 30kg

Height = 12m

Unknown:

Potential energy = ?

Solution:

Potential energy is the energy due to the position of a body.

Mathematically;

Potential energy = mgh

m is the mass

g is the acceleration due to gravity

h is the height

Now;

Potential energy = 30 x 9.8 x 12 = 3528J

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3 years ago

the 200 g baseball has a horizontal velocity of 30 m/s when it is struck by the bat, B, weighing 900 g, moving at 47 m/s. during

Ivanshal [37]

Solution :

Given :

Mass of the baseball, m = 200 g

Velocity of the baseball, u = -30 m/s

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Velocity of the baseball after struck by the bat, v = 47 m/s

According to the conservation of momentum,

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(900 x 47) + (200 x -30) = (900 x $v_1$ ) + (200 x $v_2$ )

36300 = (900 x $v_1$ ) + (200 x $v_2$ )

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$9v_1 = 363 - 2v_2$

$v_1=\frac{363 - 2v_2}{9}$

The mathematical expression for the conservation of kinetic energy is

$\frac{1}{2}Mv^2+\frac{1}{2}mu^2 = \frac{1}{2}Mv_1^2+\frac{1}{2}mv_2^2$

$\frac{1}{2}(900)(47)^2+\frac{1}{2}(200)(-30)^2 = \frac{1}{2}(900)v_1^2+\frac{1}{2}(200)v_2^2$ ................(ii)

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$21681 = 9v_1^2+2v_2^2$

Substituting (i) in (ii)

$21681= 9\left( \frac{363-2v_2}{9}\right)^2+2v_2^2$

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$(363)^2+18v_2^2-2(363)(2v_2)+(363)^2-195129=0$

$22v_2^2-145v_2-63360=0$

Solving the equation, we get

$v_2=96 \ m/s, -30 \ m/s$

The negative velocity is neglected.

Therefore, substituting 96 m/s for $v_2$ in (i), we get

$v_1=\frac{363-(2 \times 96)}{9}$

= 19

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Answer:

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