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DanielleElmas [232]

3 years ago

11

A feather is dropped on the moon from a height of 1.40 meters. The acceleration due to gravity on the moon is 1.67 m/s2. Determi

ne the time for the feather to fall on the surface of the moon.

1 answer:

RoseWind [281]3 years ago

7 0

Distance = (1/2) (acceleration) (time)²

1.4m = (0.835 m/s²) (time)²

(time)² = (1.4/0.835) s²

<em>time = 1.295 s</em>

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Which of the following choices is an example of an allele?

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Blue eye-color gene

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3. If a car is moving at 90km/hr and it rounds a corner, also at 90km/hr. Does it maintain

dolphi86 [110]

Answer:

Constant speed: yes

Constant velocity: no

Explanation:

Let's remind the definition of speed and velocity:

- Speed is a scalar quantity, which is equal to the ratio between the distance covered (regardless of the direction) and the time taken:

$s=\frac{d}{t}$

- Velocity is a vector quantity, so it has both a magnitude and a direction. The magnitude is equal to the rate between the displacement of the object and the time taken, while the direction is the same as the displacement.

In this problem, we notice that:

- The speed of the car remains constant, as it is 90 km/h

- However, its direction of motion changes while the car travels round the corner: this means that the direction of the velocity is also changing, therefore velocity is not constant.

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3 years ago

Chloe wanted to find out if the color of a food would affect how quickly kindergarten children would eat it for lunch. She belie

Harrizon [31]

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The reason this is is because she the first sentence says that she believed that people would eat the mashed potatoes faster if they were brighter color.

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3 years ago

Cesium-137 undergoes beta decay and has a half-life of 30.0 years. How many beta particles are emitted by a 14.0-g sample of ces

Mandarinka [93]

Answer: $0.81\times 10^{16}$ beta particles

Explanation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass = 14.0 g

Molar mass = 137 g/mol

$\text{Number of moles of cesium}=\frac{14.0g}{137g/mol}=0.102moles$

According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number $6.023\times 10^{23}$ of particles.

1 mole of cesium contains atoms = $6.023\times 10^{23}$

0.102 moles of cesium contains atoms = $\frac{6.023\times 10^{23}}{1}\times 0.102=0.614\times 10^{23}$

The relation of atoms with time for radioactivbe decay is:

$N_t=N_0\times \frac{1}{2}^{\frac{t}{t_{\frac{1}{2}}}}$

Where $N_t$ =atoms left undecayed

$N_0$ = initial atoms

t = time taken for decay = 3 minutes

${t_{\frac{1}{2}}}$ = half life = 30.0 years = $1.577\times 10^7$ minutes

The fraction that decays : $1-(\frac{1}{2})^{\frac{3}{1.577\times 10^7}}=1.32\times 10^{-7}$

Amount of particles that decay is = $0.614\times 10^{23}\times 1.32\times 10^{-7}=0.81\times 10^{16}$

Thus $0.81\times 10^{16}$ beta particles are emitted by a 14.0-g sample of cesium-137 in three minutes.

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3 years ago

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Aloiza [94]

Answer:

It is equal to the overall momentum before collision, so far no external object is involved.

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Momentum is always conserved during collision as a rule. This is equal to the product of the mass and velocity. Thank you.

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