After running for a while, the fan becomes hot to the touch, and ever so often releases __________________

A car moves uphill at 40 km/h and then back downhill at 60 km/h. What is the average speed for the round trip?

jok3333 [9.3K]

Answer:

$S_a_v_e_r_a_g_e=48km/h$

Explanation:

Ok, the average speed can be calculate with the next equation:

$S_a_v_e_r_a_g_e=\frac{Total\hspace{3}distance}{Total\hspace{3}time}$ (1)

Basically the car cover the same distance "d" two times, but at different speeds, so:

$Total\hspace{3}distance=2*d$

and the total time would be the time t1 required to go from A to B plus the time t2 required to go back from B to A:

$Total\hspace{3}time=t1+t2$

From basic physics we know:

$t=\frac{d}{S1}$

so:

$t1=\frac{d}{S1}$

$t2=\frac{d}{S2}$

Using the previous information in equation (1)

$S_a_v_e_r_a_g_e=\frac{2*d}{\frac{d}{S1} +\frac{d}{S2} }=\frac{2*d}{\frac{d*S2+d*S1}{S1+S2} }$

Factoring:

$S_a_v_e_r_a_g_e=\frac{2*S1*S2}{S1+S2}$ (2)

Finally, replacing the data in (2)

$S_a_v_e_r_a_g_e=\frac{2*40*60}{60+40} =48km/h$

5 0

3 years ago

Hold a pencil in front of your eye at a position where its blunt end just blocks out the Moon.

Valentin [98]

Answer:

$D = 3.55 \times 10^6 m$

Explanation:

Light rays coming from moon is blocked by the pencil

so as per figure we know that angle subtended by pencil and angle subtended by moon must be same

so we have

$Angle = \frac{Arc}{Radius}$

so we have

$\frac{D}{3.8 \times 10^8 m} = \frac{0.7 cm}{75 cm}$

so we have

$D = 3.55 \times 10^6 m$

4 0

3 years ago

ANSWER FAST PLEASE HELP

KengaRu [80]

Answer:

B. 175 N

Explanation:

Net force can be defined as the vector sum of all the forces acting on a body or an object i.e the sum of all forces acting simultaneously on a body or an object.

Mathematically, net force is given by the formula;

$Fnet = Fapp + Fg$

Where;

Fnet is the net force

Fapp is the applied force

Fg is the force due to gravitation

In this scenario, we observed that both forces are acting in the same direction.

Therefore:

Net force = 100 N + 75 N

Net force = 175 Newton

6 0

3 years ago

How is sound produced

Dafna11 [192]

Sounds are created when something vibrates (shakes back and forth), sending waves of vibrations into the ears of the listener. When a bell is struck, the metal vibrates. The vibrations travel through the air as sound waves.

hope this helps

7 0

2 years ago

Venus is often called Earth's "twin." Describe TWO ways in which Earth and Venus are similar and TWO ways in which Earth and Ven

insens350 [35]

Venus is called Earth's "Twin" because Earth and Venus have almost the same mass, size, similar composition and they are neighboring planets. Some of most notable differences though between the two planets are their color, temperature, Earth's ability to support life and their atmosphere. Venus' atmosphere is about 100x thicker than Earth's, Earth can support life while Venus can not because Earth has water and plant life and Earth is a bright blue and green while Venus is more orange and red.

8 0

3 years ago

After running for a while, the fan becomes hot to the touch, and ever so often releases ___________________ energy into the air.