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IrinaVladis [17]

2 years ago

14

During a football game, the running back changes direction from running 4.5 m/s [N] to 4.5 m/s [S] over 8 s. What is the acceler

ation of the running back during that time?

1 answer:

Nimfa-mama [501]2 years ago

8 0

Explanation:

Take north to be positive and south to be negative.

a = (v − v₀) / t

a = (-4.5 m/s − 4.5 m/s) / 8 s

a = -1.125 m/s²

The acceleration is 1.125 m/s² south.

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Why is it necessary to centrifuge out any precipitate formed in the unknown solution and continue testing the remaining unknown

jonny [76]

Answer:

Precipitation is the formation of a solid from a solution. It is necessary to centrifuge the precipitate to exert sufficient forces of gravity to bring the solid particles in the solution to come together and settle

Explanation:

When you centrifuge precipitate it enables the nucleation to form.

Centrifuging the precipitate helps in determining whether a certain element is present in a solution or not.

5 0

2 years ago

In an LC circuit containing a 40-mH ideal inductor and a 1.2-mF capacitor, the maximum charge on the capacitor is 45mC during os

GalinKa [24]

Answer:

E) 6.5 A

Explanation:

Given that

L = 40 m H

C= 1.2 m F

Maximum charge on capacitor ,Q= 45 m C

The maximum current I given as

I = Q.ω

ω =angular frequency

$\omega=\dfrac{1}{\sqrt{CL}}$

By putting the values

$\omega=\dfrac{1}{\sqrt{CL}}$

$\omega=\dfrac{1}{\sqrt{40\times 10^{-3}\times 1.2 \times 10^{-3}}}$

ω = 144.33 rad⁻¹

Maximum current

I = 45 x 10⁻³ x 144.33 A

I= 6.49 A

I = 6.5 A

E) 6.5 A

3 0

3 years ago

If one half-life is 60 seconds, how old is the sample after 5 half-lives?

yuradex [85]

Answer: 300 years old

Explanation: 60x5=300

4 0

2 years ago

Read 2 more answers

A rocket car on a horizontal rail has an initial mass of 2500 kg and an additional fuel mass of 1000 kg. At time t0 the rocket m

slamgirl [31]

Answer: Acceleration of the car at time = 10 sec is 108 $m/s^{2}$ and velocity of the car at time t = 10 sec is 918.34 m/s.

Explanation:

The expression used will be as follows.

$M\frac{dv}{dt} = u\frac{dM}{dt}$

$\int_{t_{o}}^{t_{f}} \frac{dv}{dt} dt = u\int_{t_{o}}^{t_{f}} \frac{1}{M} \frac{dM}{dt} dt$

= $u\int_{M_{o}}^{M_{f}} \frac{dM}{M}$

$v_{f} - v_{o} = u ln \frac{M_{f}}{M_{o}}$

$v_{o} = 0$

As, $v_{f} = u ln (\frac{M_{f}}{M_{o}})$

u = -2900 m/s

$M_{f} = M_{o} - m \times t_{f}$

= $2500 kg + 1000 kg - 95 kg \times t_{f}s$

= $(3500 - 95t_{f})s$

$v_{f} = -2900 ln(\frac{3500 - 95 t_{f}}{3500}) m/s$

Also, we know that

a = $\frac{dv_{f}}{dt_{f}} = \frac{u}{M} \frac{dM}{dt}$

= $\frac{u}{3500 - 95 t} \times (-95) m/s^{2}$

= $\frac{95 \times 2900}{3500 - 95t} m/s^{2}$

At t = 10 sec,

$v_{f}$ = 918.34 m/s

and, a = 108 $m/s^{2}$

3 0

2 years ago

The current estimate for the age of earth of 4.57 ga comes from _____.

Whitepunk [10]

The estimation of the age of the Earth comes from scientists who studied the rock formation under the Earth's crust. They believe that during the Big Bang, the Earth, together with the other celestial bodies in the universe, were formed. Under the Earth's soil contain radioactive materials that have known decay rates. Using these rate, they undergo tests like rock dating to find the time of its existence.

4 0

2 years ago