What sort of waves exhibit the doppler effect?

How should i fix an overfilled ballon? its my sisters 3rd birthday and i have overfilled all the ballons and there is no other o

iVinArrow [24]

Try to untie the knot and let a little air out and tie it back.....

8 0

3 years ago

A voltage amplifier needs a high input resistance and a low output resistance. Select one: True False

cupoosta [38]

Answer:

Explanation:

In electric circuit , the potential difference is always developed across the resistance .

Now is we are to amplify the voltage , that means low input voltage is converted into high voltage output .

Therefore we require low resistance at input for low voltage and high out put resistance for high output

Thus the statement given is wrong .

6 0

3 years ago

The kinetic energy of a moving object is E=12mv2. A 61 kg runner is moving at 10kmh. However, her speedometer is only accurate t

jek_recluse [69]

Answer:

$e=3367.2J$

% $e=1.43$ %

Explanation:

From the exercise we know two information. The real speed and the experimental measured by the speedometer

$v_{r}=10km/h=2.77m/s$

Since the speedometer is only accurate to within 0.1km/h the experimental speed is

$v_{e}=10km/h-0.1km/h=9.9km/h=2.75m/s$

Knowing that we can calculate Kinetic energy for the real and experimental speed

$E_{r}=\frac{1}{2}mv^2=\frac{1}{2}(61000g)(2.77m/s)^2=234023J$

$E_{e}=\frac{1}{2}mv^2=\frac{1}{2}(61000g)(2.75m/s)^2=230656J$

Now, the potential error in her calculated kinetic energy is:

$e=E_{r}-E_{e}=(234023-230656)J=3367.2J$

% $e=\frac{E_{r}-E_{e}}{E_{r}}x100=\frac{(234023-230656)J}{234023J}x100=1.43$ %

4 0

4 years ago

1) What kind of energy is gained when your roller coaster goes uphill?

Dvinal [7]

1) Gravitational potential energy

In fact, gravitational potential energy is given by: $GPE=mgh$

where m is the mass of the roller coaster, g is the gravitational acceleration and h is the heigth. Therefore, when the roller coaster goes uphill, the height h increases and the roller coaster gains gravitational potential energy.

2) The relationship between potential and kinetic energy is:

$M.E.=K.E.+G.P.E.$

where ME is the total mechanical energy, KE is the kinetic energy, GPE is the gravitational potential energy. Since the value of ME is constant (when no friction is present), this means that when KE increases, GPE decreases, and vice-versa.

3) If friction is removed from the track, the roller coaster would move forever. In fact, in the equation written in part 2), ME is constant only in case there is no friction - when friction is present, part of the energy is lost due to the friction, so the total ME available decreases little by little until it becomes zero, and the roller coaster cannot move anymore.

4) It matters because it affects the magnitude of the friction. In fact, friction is given by

$F=\mu mg$

where $\mu$ is the coefficient of friction, m is the mass ,and g the gravitational acceleration. When the number of carts is increased, the mass increases, therefore the friction increases as well.