The strength of the electric field of a charged particle becomes greater as the distance from the particle increases. T F

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 71 m/s.

The bullet of mass m moving with a velocity u 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 v when it emerges from the block.

If the block exerts a resistive force F on the bullet and the thickness of the block is x 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 v₁.

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 v₁.

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

Thus the speed of the bullet is 71 m/s

3 0

3 years ago

A 20-kg child is tossed up into the air by her parent. The child is 2 meters off the ground traveling 5 m/s.

nignag [31]

The kinetic energy (KE) is 250 J and the gravitational potential energy (GPE) is 392 J

4 0

3 years ago

GIVING BRAINLIEST PLEASE HELP ME!!!

kumpel [21]

Answer:

I'm Pretty sure the answer your looking for is C

4 0

2 years ago

Es

nexus9112 [7]

Answer:

As the skydiver falls to the Earth, she experiences positive acceleration only due to gravity.

Explanation:

As the skydiver falls to the Earth, she experiences friction in the form of air resistance which tries to slow her down and is proportional to the her velocity. So it cannot have a positive acceleration as it acts in opposite direction to slow her down.

Inertia during skydiving is experienced when we open an parachute, the parachute slows down the speed of are descent hence changing our inertia of motion with a velocity.

Only the Earth's, gravitational field has an positive acceleration as it pulls us towards the Earth, hence increasing our velocity.

3 0

3 years ago

A hemisphere is __________ of the Earth.

grin007 [14]

A- a hemisphere is one half of earth.

8 0

3 years ago