3 years ago

Plz tll answer of this . pleaseeeeeeeeeeee. Q 6,7,8

Physics

1 answer:

777dan777 [17]3 years ago

8 0

Can someone pls help us with this question I need the answer too

You might be interested in

Find the wavelength λ of the 80.0-khz wave emitted by the bat. express your answer in millimeters.

vfiekz [6]

Answer:

4.29 millimeters

Explanation:

Bats emit ultrasound waves: in air, ultrasound waves travel at a speed of

$v=343 m/s$

The frequency of the waves emitted by this bat is:

$f=80.0 kHz = 80,000 Hz$

Therefore we can find the wavelength of the wave emitted by the bat by using the relationship between speed, frequency and wavelength:

$\lambda=\frac{v}{f}=\frac{343 m/s}{80,000 Hz}=4.29\cdot 10^{-3} m=4.29 mm$

4 0

3 years ago

Consider a rocket that is in deep space and at rest relative to an inertial reference frame. The rocket's engine is to be fired

ValentinkaMS [17]

Answer:

$\frac{m_i}{m_f}=2.7182$

$\frac{m_i}{m_f}=1096.633$

Explanation:

$m_i$ = Initial mass of rocket

$m_f$ = Final mass of rocket

u = Initial velocity

$v_r$ = Relative velocity

v = Velocity

From the rocket equation

$v=u+v_{r}\ln {\frac {m_{i}}{m_{f}}}\\\Rightarrow v=v_{r}\ln {\frac {m_{i}}{m_{f}}}\\\Rightarrow \frac{m_i}{m_f}=e^{\frac{v}{v_{r}}}\\\Rightarrow \frac{m_i}{m_f}=e^{\frac{v}{v}}=e^1\\\Rightarrow \frac{m_i}{m_f}=2.7182$

$\frac{m_i}{m_f}=2.7182$

when $v=7v_r$

$v=v_{r}\ln {\frac {m_{i}}{m_{f}}}\\\Rightarrow \frac{m_i}{m_f}=e^{\frac{v}{v_{r}}}\\\Rightarrow \frac{m_i}{m_f}=e^{\frac{7v_r}{v_r}}=e^7\\\Rightarrow \frac{m_i}{m_f}=1096.633$