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3 years ago

- Speed is a scalar, a quantity that is described by alone.

Physics

1 answer:

Savatey [412]3 years ago

5 0

Answer:

True

Explanation:

Thats is true since it cannot be a vector because speed only gives a magnitude, not a direction as well.

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An ambulance with a siren emitting a whine at 1790 Hz overtakes and passes a cyclist pedaling a bike at 2.36 m/s. After being pa

Deffense [45]

Answer:

The speed of the ambulance is 4.30 m/s

Explanation:

Given:

Frequency of the ambulance, f = 1790 Hz

Frequency at the cyclist, f' = 1780 Hz

Speed of the cyclist, v₀ = 2.36 m/s

let the velocity of the ambulance be 'vₓ'

Now,

the Doppler effect is given as:

$f'=f\frac{v\pm v_o}{v\pm v_x}$

where, v is the speed of sound

since the ambulance is moving towards the cyclist. thus, the sign will be positive

thus,

$v_x=\frac{f}{f'}(v+v_o)-v$

on substituting the values, we get

$v_x=\frac{1790}{1780}(343+2.36)-343$

vₓ = 4.30 m/s

Hence, <u>the speed of the ambulance is 4.30 m/s</u>

6 0

3 years ago

Kelli weighs 440 N, and she is sitting on a playground swing that hangs 0.41 m above the ground. Her mom pulls the swing back an

kifflom [539]

Answer:

Explanation:

Initial height from the ground = .41 m

Final height = 1m

Height by which Kelli was raised ( h )= .59 m

When she passes through the lowest point , she loses P E

= mgh

= 440 x .59

= 259.6 J

kinetic energy possessed by her

= 1/2 mv²

= .5 x (440/9.8) x 2²

= 89.8 J

Difference of energy is lost due to work by air friction

work done by friction = 89.8 - 259.6

= - 169.8 J

4 0

3 years ago

what times are the moon phases visible? My science teacher said that the phases of the moon are only visible at sertant times of

klio [65]

Your teacher is right. The moon can be seen early in the morning sometimes and late at night. Different phases are only visible on certain days as one day might be full quarter, the next full moon, the next first quarter, etc.

6 0

3 years ago

A 1kw electric heater is switched on for ten minutes. how much heat does it produce

Ainat [17]

H= P × t

1kW= 1000w

10 min = 600s

H= 1000×600=600,000J

=> 143.40kcal

4 0

3 years ago

URGENT <br><br> Give three examples of models that you see every day

umka2103 [35]

Models are very common. The ingredients list on a bottle of ketchup is a model of its contents, and margarine is a model of butter. A box score from a baseball game is a model of the actual event. A trial over an automobile accident is a model of the actual accident.

7 0

2 years ago