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3 years ago

9

5. Why are ceramics and plastics good insulators?

1 answer:

jeka57 [31]3 years ago

3 0

Answer:

Here

Explanation:

They don't have free electrons moving around (delocalised electrons) so they can't conduct heat and electricity which gives them a property of good insulators. The insulators stop us having an electric shock because they don't conduct electricity as we use them to insulate metal wires and other metallic things. can i have brainliest now pls!

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The volume of the moon is about 33% of the volume of the earth.true or false

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The moons volume is that of 2 percent of the earth.

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A family car has a mass of 1400 kg. In an accident it hits a wall and goes from a speed of 27 m/s to a standstill in 1.5 seconds

horrorfan [7]

Answer:

The force has been reduced by 8018 N

Explanation:

The impulse exerted on the car during the crash is equal to the product of the force exerted and the duration of the collision, and it is also equal to the change in momentum of the car. So we can write:

$F\Delta t = m\Delta v$

where:

F is the force exerted on the car

$\Delta t$ is the duration of the collision

m = 1400 kg is the mass of the car

$\Delta v=-27 m/s$ is the change in velocity of the car

We can re-write the equation as

$F=\frac{m\Delta v}{\Delta t}$

In the 1st collision, the time is 1.5 seconds, so the force is

$F_1=\frac{(1400)(-27)}{1.5}=-25,200 N$

In the 2nd collision, the time is increased to 2.2 seconds, so the force is

$F_2=\frac{(1400)(-27)}{2.2}=-17,182 N$

Therefore, the force has been reduced by:

$F_2-F_1=-17,182-(-25,200)=8018 N$

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4 years ago

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Which statement best describes how light waves travel in a uniform medium?

Zanzabum

The statement which best describes how light waves travel in an uniform medium is in straight lines. The correct answer will be A.

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3 years ago

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A large crane consists of a 20 m, 3,000 kg arm that extends horizontally on top of a vertical tower. The arm extends 15 m toward

Anni [7]

Answer:

$m=18000kg$

Explanation:

From the question we are told that:

Crane Length $l=20m$

Crane Mass $m_a=3000kg$

Arm extension at lifting end $l_l=15m$

Arm extension at counter weight end $l_c=5m$

Load $M_l=5000kg$

Generally the equation for Torque Balance is mathematically given by

$T_1 *l_c-(m_a*g) *l_c-(T_2)*l_l=0$

$mg*5 *-(3000*9.8) *5-(5000*9.8)*15=0$

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3 years ago

A coin released at rest from the top of a tower hits the ground after falling 5.7 s. What is the speed of the coin as it hits th

Bad White [126]

Given parameters:

Initial velocity of Coin = 0m/s

Time taken before coin hits ground = 5.7s

Unknown:

Final velocity of the coin = ?

Velocity is displacement with time. To solve this problem, we have to apply one of the equations of motion.

The fitting one of them here is shown below;

V = U + gt

where;

V is the final velocity

U is the initial velocity

g is the acceleration due to gravity

t is the time taken

Here we use positive value of acceleration due to gravity because the coin is falling with the effect of acceleration and not against it.

Now input the parameters and solve;

V = 0 + 9.81 x 5.7

V = 55.917m/s

Therefore, the final velocity is 55.917m/s.

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