A rock falls off a cliff and falls for 3 secs. How high was the cliff?

A fish finder uses a sonar device that sends 20,000-Hz sound pulses downward from the bottom of the boat, and then detects echoe

mrs_skeptik [129]

Answer: The minimum time between pulses (in fresh water)

= 0.3106 s

Explanation:

To calculate the speed of echoes sounds, we will use

Speed = 2x/t

Where x = distance and t = total time.

Please note that:

sound travels at 343 m/s in air. But it travels at 1,481 m/s in water (almost 4.3 times as fast as in air);

Total distance = 2 × 230 = 460m

Using speed of sound in water

1481 = 460/t

t = 460/1481

t = 0.3106

3 0

3 years ago

hat are the wavelengths of peak intensity and the corresponding spectral regions for radiating objects at (a) normal human body

bagirrra123 [75]

Answer:

(a)

$\lambda _{m}=9.332 \times 10^{-6}m$

(b)

$\lambda _{m}=1.632 \times 10^{-6}m$

(c) $\lambda _{m}=4.988 \times 10^{-7}m$

Explanation:

According to the Wein's displacement law

$\lambda _{m}\times T = b$

Where, T be the absolute temperature and b is the Wein's displacement constant.

b = 2.898 x 10^-3 m-K

(a) T = 37°C = 37 + 273 = 310 K

$\lambda _{m}=\frac{b}{T}$

$\lambda _{m}=\frac{2.893\times 10^{-3}}{310}$

$\lambda _{m}=9.332 \times 10^{-6}m$

(b) T = 1500°C = 1500 + 273 = 1773 K

$\lambda _{m}=\frac{b}{T}$

$\lambda _{m}=\frac{2.893\times 10^{-3}}{1773}$

$\lambda _{m}=1.632 \times 10^{-6}m$

(c) T = 5800 K

$\lambda _{m}=\frac{b}{T}$

$\lambda _{m}=\frac{2.893\times 10^{-3}}{5800}$

$\lambda _{m}=4.988 \times 10^{-7}m$

5 0

3 years ago

Voltage will be induced in a wire loop when a magnetic field within that loopa. is at right angles to the electric field b. chan

mixas84 [53]

Answer:

changes

Explanation:

According to Michael Faraday, voltage is induced on a metallic conductor when the magnetic field changes. The principle is known as the principle of electromagnetic induction. The voltage induced on the metallic conductor is referred to as induced emf.

The magnitude if induced emf depends on the rate of change of the magnetic flux.

3 0

3 years ago

A bicycle and a car start their journey at the same time the cyclist reaches it's top speed of 10mls in 15 the car reaches a spe

Y_Kistochka [10]

Complete question is;

A bicycle and a car start their journey at the same time the cyclist reaches it's top speed of 10m/s in 15 s, the car reaches a speed of 15 m/s in 55 s. which has the greater acceleration the car or the bicycle.

Answer:

The bicycle has the greater acceleration.

Explanation:

Cyclist reaches a top speed of 10m/s in 15 s.

Formula for acceleration here is;

a = v/t

a = 10/15

a = 0.67 m/s²

Car reaches a speed of 15 m/s in 55 s.

Thus;

a = 15/55

a = 0.27 m/s²

From the 2 acceleration values gotten, we can say that;

The bicycle has the greater acceleration.

6 0

3 years ago

What is an equal and opposite force to gravity

muminat

Gravity is the equal and opposite force to gravity. If object A pulls object B with some force, object B pulls on object A equally.

4 0

3 years ago