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2 years ago

In which of the following situations is the Doppler effect absent?

1 answer:

4 0

The source and the observer are moving towards each other. The observer is moving toward the source. The source is moving away from the observer

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Determine the stopping distances for a car with an initial speed of 88 km/h and human reaction time of 2.0 s for the following a

seropon [69]

Explanation:

Given that,

Initial speed of the car, u = 88 km/h = 24.44 m/s

Reaction time, t = 2 s

Distance covered during this time, $d=24.44\times 2=48.88\ m$

(a) Acceleration, $a=-4\ m/s^2$

We need to find the stopping distance, v = 0. It can be calculated using the third equation of motion as :

$s=\dfrac{v^2-u^2}{2a}$

$s=\dfrac{-(24.44)^2}{2\times -4}$

s = 74.66 meters

s = 74.66 + 48.88 = 123.54 meters

(b) Acceleration, $a=-8\ m/s^2$

$s=\dfrac{v^2-u^2}{2a}$

$s=\dfrac{-(24.44)^2}{2\times -8}$

s = 37.33 meters

s = 37.33 + 48.88 = 86.21 meters

Hence, this is the required solution.

4 0

2 years ago

What item can be arranged to transform electrical energy to mechanical energy

meriva

Answer:

battery iron wire

Explanation:

7 0

2 years ago

The lanthanides are all radioactive true or false

Oksi-84 [34.3K]

Answer:

False

Explanation:

All the lanthanides are not radioactive in nature. Just one of the lanthanides are radioactive.

The lanthanides belong to the f-block on the periodic table
Only Promethium in this group are radioactive in nature.
Other elements in the lanthanide series might have radioactive isotopes.

3 0

2 years ago

Ciara is swinging a 0.015 kg ball tied to a string around her head in a flat, horizontal circle. The radius of the circle is 0.5

Marat540 [252]

Answer:

Option C

Explanation:

From the question we are told that:

Mass $m=0.015kg$

Radius $r=0.5m$

Time $t=0.70$

Generally the equation for Tension is mathematically given by

$T=\frac{4mr}{t^2} \pi$

$T=\frac{4*0.015*0.5}{(0.70)^2} (3.142)$

$T=0.60N$

Therefore

$T=0.60 N$ , toward the center of the circle

Option C

3 0

2 years ago

Iwill need to use more force to stopa<br> O Lighter mass<br> O Heavier mass

trasher [3.6K]

Answer:

a heavier mass

Explanation:

7 0

2 years ago