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3 years ago

10

Explain why materials such as plastic foam, feathers, and fur are poor conductors of heat.

1 answer:

Firlakuza [10]3 years ago

7 0

The atoms of some materials have no free electrons in their outer orbits. These electrons are busy doing other jobs, like being shared in the orbits of two adjacent atoms. They are so closely held that it is very difficult to pull them away. Most compounds of carbon and hydrogen are like this.

<span>Plastics, whose molecules are made from long combinations of carbon and hydrogen atoms, have few or no free electrons. This means that plastics are poor conductors of electricity (and they are also poor conductors of heat). hope that helped.</span>

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A toy car is given a quick push so that it moves up an inclined ramp. After it is released, it moves up, reaches its highest poi

Alexeev081 [22]

Answer:

7. Net constant force down the ramp

Explanation:

After the car is released and starts moving up the ramp, the only force that is applied on the car is weight because of the gravity, we were told that the friction force is neglected. the force because of the weight is given by:

$F=m*g*sin(\theta)$

where θ is the angle of the ramp.

as you can see those values won't change, so the force remains constant down the ramp.

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3 years ago

Sound is.....<br> A. matter<br> B. Vibration<br> C. potential energy<br> D. electromagnetic energy

Shkiper50 [21]

The answer is C. Potential energy

(I learned this in class recently)

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3 years ago

A hockey player strikes a puck, giving it an initial velocity of 14.0 m/s in the positive x-direction. The puck slows uniformly

Advocard [28]

a) $-1.71 m/s^2$

b) 7.7 m/s

c) 4.39 s

Explanation:

a)

The acceleration of an object is the rate of change of velocity of an object.

In this problem, the acceleration of the puck can be found using the following suvat equation:

$v^2-u^2=2as$

where:

v is the final velocity

u is the initial velocity

a is the acceleration

s is the distance travelled

For the puck in this problem:

u = 14.0 m/s

v = 6.50 m/s

s = 45.0 m

So, the acceleration is:

$a=\frac{v^2-u^2}{2s}=\frac{6.50^2-14.0^2}{2(45.0)}=-1.71 m/s^2$

b)

The velocity of the puck at time t can be found by using another suvat equation:

$v=u+at$

where

u is the initial velocity

a is the acceleration

t is the time elapsed

v is the final velocity

Here, we have:

u = 14.0 m/s

$a=-1.71 m/s^2$ (found in part a)

Therefore, the velocity of the puck after t = 3.70 s is:

$v=14.0+(-1.71)(3.70)=7.7 m/s$

c)

Here we want to find the time taken for the puck to travel a distance of

s = 45.0 m

To solve this part, we can use again the suvat equation:

$v=u+at$

Where in this case, we use:

u = 14.0 m/s is the initial velocity

v = 6.50 m/s is the final velocity when the puck has travelled 45.0 m (this information is given in the question)

$a=-1.71 m/s^2$ is the acceleration (found in part a)

Therefore, by re-arranging the equation, we find the time taken to cover 45.0 m:

$t=\frac{v-u}{a}=\frac{6.50-14.0}{-1.71}=4.39 s$

7 0

3 years ago

This equation shows the reaction that occurs when charcoal burns. What type<br> of reaction is it?

TiliK225 [7]

Explanation:

Exothermic

Because here Energy is released.

3 0

3 years ago

Read 2 more answers

When the mallet hits the ball with an action force, the ball exerts a reaction force on the mallet, as explained by ___

satela [25.4K]

Answer:

Newton's third law of motion.

Explanation:

Every action has an equal and opposite reaction.

4 0

3 years ago