Which of the following elements would not be considered a nonmetal

The law of conservation of energy states that: "energy cannot be created nor destroyed. It can only be transformed from one form to the other". A heat pump transfers heat from a colder area to a warmer area. As the conservation of energy goes, the energy that comes in, must equal the energy that comes out. Although no machine is 100% efficient, the missing energy is supplied by an external energy source, such as electricity.

4 0

4 years ago

What frequency is received by the ambulance after reflecting from a wall near the person watching the oncoming ambulance (as in

ElenaW [278]

Answer:

f=896Hz

Explanation:

Given data

Vs(speed of the ambulance)={(104 km/h)*(1000m*(1 h/3600)}=28.9m/s

f(frequency of the ambulance siren)=821 Hz

v(speed of sound)=345 m/s

Vo(speed of the observer)=0 m/s

To find

f(The ambulance is approaching the person)

Solution

From Doppler effect

$f^{i}=(\frac{v+v_{o} }{v-v_{s} })f$

As the ambulance approaches the we assign a positive sign for speed "vs" of the ambulance

So

$f^{i}=(\frac{v+0}{v-(+v_{s}) } )f\\f^{i}=(\frac{v}{v-v_{s} } )f$

Substitute the values from given data

$f^{i}=(\frac{345m/s}{345m/s-28.9m/s} )821Hz\\f^{i}=896Hz$

5 0

3 years ago

Velocity and acceleration are both vectors; they have a direction. What is thedirection of the velocity and acceleration vectors

just olya [345]

Answer:

d. Both A & C

Explanation:

- The velocity of the ball is a vector, whose magnitude indicates its rate of change of position, and it has a direction. In this case, the ball is moving upward, therefore the direction of motion is upward, so the direction of the velocity is upward as well.

- The acceleration of the ball is a vector, whose magnitude indicates the rate of change of the velocity. The direction of the acceleration is:

-- positive if the the magnitude of the velocity is increasing

-- negative if the magnitude of the velocity is decreasing

For a ball thrown upward, the acceleration is given by the acceleration of gravity, $g=9.8 m/s^2$ . This acceleration points downward, and it is constant during the entire motion. In particular, it does not change direction, as it is always directed downward. Therefore, the acceleration of the ball is downward.

So, the correct answer is

d.Both A & C

Since A and C are both true:

a.The velocity vector is directed upward.

c.The acceleration is directed downward.

3 0

3 years ago