All categories

4 years ago

The friction force that acts on objects that are at rest is___________

Physics

1 answer:

weeeeeb [17]4 years ago

7 0

Answer:

static friction

Explanation:

static friction is the friction force that acts on objects at rest

You might be interested in

Which planet is the farthest terrestrial planet from the Sun?

Ivanshal [37]

THE ANSWER IS B.MERCURY

4 0

3 years ago

A book prone to air resistance is released from rest 300 m

yaroslaw [1]

Answer:

Approximately $73\%$ .

(Assuming that $g = \rm 9.81\; m \cdot s^{-2}$ .)

Explanation:

The mechanical energy of an object is the sum of its potential energy and its kinetic energy. It will be shown that the exact mass of this object doesn't matter. For ease of calculation, let $m(\text{book})$ represent the mass of the book.

The initial potential energy of the book is

$\begin{aligned}U(300\; \text{m}) &= m(\text{book}) \cdot g \cdot \Delta h + U(0\; \text{m}) \cr &=(9.81 \times 300) \cdot m(\text{book})\cr &= \left(2.943\times 10^3\right) \cdot m(\text{book})\end{aligned}$ .

The book was initially at rest when it was released. Hence, its initial kinetic energy would be zero. Hence, the initial mechanical energy of the book-Earth system would be $(2.943\times 10^3) \cdot m(\text{book})$ .

When the book was about to hit the ground, its speed is $\rm 40\; m \cdot s^{-1}$ . Its kinetic energy would be:

$\begin{aligned} \text{KE} &= \frac{1}{2} \, m(\text{book}) \cdot v^{2} \cr &= \left(\frac{1}{2} \times 40^2\right)\cdot m(\text{book}) \cr &= \left(8.00\times 10^2\right)\cdot m(\text{book})\end{aligned}$ .

The question implies that the potential energy of the book near the ground is zero. Hence, the mechanical energy of the system would be $\left(8.00\times 10^2\right)\cdot m(\text{book})$ when the book was about to hit the ground.

The amount of mechanical energy lost in this process would be equal to:

$\begin{aligned}&\left(2.943\times 10^3\right) \cdot m(\text{book}) - \left(8.00\times 10^2\right)\cdot m(\text{book}) \cr &=\left(2.143\times 10^3\right)\cdot m(\text{book})\end{aligned}$ .

Divide that with the initial mechanical energy of the system to find the percentage change. Note how the mass of the book, $m(\text{book})$ , was eliminated in this process.

$\begin{aligned}&\frac{\left(2.143\times 10^3\right)\cdot m(\text{book})}{\left(2.943\times 10^3\right) \cdot m(\text{book})}\times 100\% \cr &= \frac{2.143\times 10^3}{2.943\times 10^3}\times 100\% \cr & \approx 73\%\end{aligned}$ .

5 0

4 years ago

This boy uses a force to lift a heavy rock. (He is carrying it.) What can the boy do if he wants to lift the same rock more quic

lutik1710 [3]

I nthink the answer is c may be

5 0

3 years ago

Read 2 more answers

Question: As the moon spins on its axis we see

butalik [34]

Answer:

<h2><em><u>A) Different parts of the moon throughout the month</u></em></h2>

Explanation:

Every thing I researched on the moon never says you can see all sides of the moon while its spinning expect the full moon. Your gonna see different sides of the moon because it is spinning not staying still. The last one is wrong because the moon goes threw a cycle. (sorry if anything is wrong this is just what I've been learning and understanding about the moon)

5 0

3 years ago

What is a Homonym for a type of cloak?

blsea [12.9K]

Answer:

In both cases, the sound and spelling are the same, and only the definition changes. Here are 30 more examples of homonyms. Note that some homonyms have more than two meanings (for example, "tender" can also mean sensitive, easily chewed, or even refer to chicken strips), but to keep things simple we've only included two in our homonyms list:

8 0

3 years ago