When does a scientist create the conclusion?

The driver of a stationary car hears a siren of an approaching police car at a frequency of 280Hz. If the actual frequency of th

deff fn [24]

Answer:

The speed of the police car is 294 m/s

Explanation:

Given;

frequency of the siren in air, f = 280 Hz

speed of sound in air, v = 343 m/s

Determine the wavelength of the sound in air to the stationary car:

v = fλ

where;

λ is wavelength of the sound

λ = v/f

λ = 343 / 280

λ = 1.225 m

Now, determine the speed at which the police car is approaching the stationary car;

The actual frequency of the police car, F = 240 Hz

V = Fλ

Where;

V is speed of the police car

λ is the distance between the police car and the stationary car, (wavelength)

V = 240 x 1.225

V = 294 m/s

Therefore, the speed of the police car is 294 m/s

5 0

3 years ago

Which of the following has to happen for Earth's shadow to fall on the moon?

Ronch [10]

The correct answer is a, lunar eclipse

6 0

3 years ago

During a braking test, a car is brought to rest beginning from an initial speed of 60 mi/hr in a distance of 120 ft. With the sa

maw [93]

Answer:

Explanation:

Given

Initial speed $u=60\ mi/hr\approx 88\ ft/s$

distance traveled before coming to rest $d_1=120\ ft$

using equation of motion

$v^2-u^2=2as$

where v=final velocity

u=initial velocity

a=acceleration

s=displacement

$0-(88)^2=2\times a\times 120---1$

for $u_2=80\ mi/hr\approx 117.33\ ft/s$

using same relation we get

$0-(117.33)^2=2\times a\times (d_2)----2$

divide 1 and 2 we get

$(\frac{88}{117.33})^2=\frac{120}{d_2}$

$d_2=213.32\ ft$

So a distance if 213.32 ft is required to stop the vehicle with 80 mph speed

8 0

3 years ago

You are a detective investigating why someone was hit on the head by a falling flowerpot. One piece of evidence is a smartphone

umka21 [38]

Answer:

0.37 m

Explanation:

Given :

Window height, $h_1$ = 1.27 m

The flowerpot falls 0.84 m off the window height, i.e.

$h_2$ = (1.27 x 0.84 ) m in a time span of $t=\frac{8}{30}$ seconds.

Assuming that the speed of the pot just above the window is v then,

$h_2=ut+\frac{1}{2}gt^2$

$(1.27 \times 0.84) = v \times \left( \frac{8}{30} \right) + \frac{1}{2} \times 9.81 \times \left( \frac{8}{30} \right)^2$

$v=\left(\frac{30}{8}\right) \left[ (1.27 \times 0.84) - \left( \frac{1}{2} \times 9.81 \times \left( \frac{8}{30 \right)^2 \right) \right]}$

$v= 2.69$ m/s

Initially the pot was dropped from rest. So, u = 0.

If it has fallen from a height of h above the window then,

$h = \frac{v^2}{2g}$

$h = \frac{(2.69)^2}{2 \times 9.81}$

h = 0.37 m

3 0

3 years ago

A charged particle moving along the +x-axis enters a uniform magnetic field pointing along the +z-axis. A uniform electric field

Brums [2.3K]

Answer:

the electric field direction should be in positive y axis

Explanation:

Lets assume that charge on particle is positive and it isequal to +q

First calculate the magnetic force on it

$F_B = q V\times B =qVBsin\theta$

for direction

use Right Hand Rule which will give the direction and by using his the direction will come towards negative y axis.

As given in the question that charge particle does not change their velocity so we need to apply electric field in such a way that electric force direction should be opposite to the magnectic field.

and magnitude should be same as magnectic force and also direcion of electric force depend on the direction of elecric field when charge is positive because electric force $F_E = qE$

Hence the electric field direction should be in positive y axis

3 0

4 years ago