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dimulka [17.4K]

3 years ago

14

Compare the results of applying the acceleration equation in the following 2 cases : (1) an object that goes from 0 to 10 m/s in

4 s , and (2) then goes from 10 m/s to 30 m/s in 8s.
a= (Vf-Vs)/t

1 answer:

erastovalidia [21]3 years ago

8 0

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a bullet moving with a velocity of 100m/s pierce a block of wood and moves out with a velocityof 10 m/s.if the thickness of the

erma4kov [3.2K]

The emerging velocity of the bullet is <u>71 m/s.</u>

The bullet of mass <em>m</em> moving with a velocity <em>u</em> has kinetic energy. When it pierces the block of wood, the block exerts a force of friction on the bullet. As the bullet passes through the block, work is done against the resistive forces exerted on the bullet by the block. This results in the reduction of the bullet's kinetic energy. The bullet has a speed <em>v</em> when it emerges from the block.

If the block exerts a resistive force <em>F</em> on the bullet and the thickness of the block is <em>x</em> then, the work done by the resistive force is given by,

$W=Fx$

This is equal to the change in the bullet's kinetic energy.

$W=Fx=\frac{1}{2} m(u^2-v^2)......(1)$

If the thickness of the block is reduced by one-half, the bullet emerges out with a velocity v<em>₁.</em>

Assuming the same resistive forces to act on the bullet,

$F(\frac{x}{2} )=\frac{1}{2} m(u^2-v_1^2)......(2)$

Divide equation (2) by equation (1) and simplify for v<em>₁.</em>

$\frac{\frac{Fx}{2} }{Fx} =\frac{(u^2-v_1^2)}{(u^2-v^2)} \\\frac{100^2-v_1^2}{100^2-10^2} =\frac{1}{2} \\v_1^2=5050\\v_1=71.06 m/s$

Thus the speed of the bullet is 71 m/s

3 0

3 years ago

A +12 Î¼C charge and -8 Î¼C charge are 4 cm apart. Find the magnitude and direction of the E-field at the point midway between t

Natasha_Volkova [10]

Answer:

Explanation:

Given

Charge of first Particle $q_1=+12\ \mu C$

Charge of second Particle $q_2=-8\ \mu C$

distance between them $d=4\ cm$

$k=9\times 10^{9}$

magnetic field due to first charge at mid-way between two charged particles is

$E_1=\frac{kq_1}{r^2}$

$r=\frac{d}{2}=\frac{4}{2}=2\ cm$

$E_1=\frac{9\times 10^9\times 12\times 10^{-6}}{(2\times 10^{-2})^2}$

$E_1=27\times 10^7\ N/C$ (away from it)

Electric field due to $q_2=-8\ \mu C$

$E_2=\frac{kq_2}{r^2}$

$E_2=-\frac{9\times 10^9\times 8\times 10^{-6}}{(2\times 10^{-2})^2}$

$E_2=-18\times 10^7\ N/C$ (towards it)

$E_{net}=E_1+E_2$

$E_{net}=9\times 10^7\ N/C$ (away from first charge)

8 0

3 years ago

One drawback of dams is that they can flood land upstream from the dam and reduce water flow downstream from the dam. Question 2

vivado [14]

Answer:

True

Explanation:

It can cause flooding and destruction of habitat because of dammed rivers create large reservoirs upstream which can spill out to the surrounding during heavy rainfall causing flooding and destruction of natural habitat.

7 0

3 years ago

What is the average speed of a kangaroo that hops 60 m in 5 s ?

jok3333 [9.3K]

The formula for average speed is
$v_{avg}= \frac{total distance}{total time}$
So we can just substitute our data.
$v_{avg}= \frac{60}{5}=12 \frac{m}{s}$ - its the result

6 0

3 years ago

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Plzzzzzz help!!!!!!struggling

wel

Metamorphic rock
Coal
Changes in pressure.
the matching will be in comments

4 0

3 years ago

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