3. A ball rolls along the floor with a constant velocity of 12 m/s. How far will it have gone

How does the electric force vary with distance

wlad13 [49]

The size of the force varies inversely as the square of the distance between the two charges. Therefore, if the distance between the two charges is doubled, the attraction or repulsion becomes weaker, decreasing to one-fourth of the original value.

3 0

2 years ago

Please help! I’ll give brainliest! :)

jeka94

Answer:

C.) Gravity

Explanation:

The projectile is an object upon which the only force is gravity. Gravity acts to influence the vertical motion of the projectile.

6 0

3 years ago

Justin Bieber is thrown horizontally at 10.0 m/s from the top of a cliff 122.5 m high.

sveticcg [70]

===> Distance fallen from rest in free fall =

   (1/2) (acceleration) (time²)

   (122.5 m) = (1/2) (9.8 m/s²) (time²)

Divide each side by (4.9 m/s²): (122.5 m / 4.9 m/s²) = time²

   (122.5/4.9) s² = time²

Take the square root of each side: 5.0 seconds

===> (Accelerating at 9.8 m/s², he will be dropping at
   (9.8 m/s²) x (5.0 s) = 49 m/s
when he goes 'splat'. We'll need this number for the last part.)

===> With no air resistance, the horizontal component of velocity
doesn't change.

Horizontal distance = (10 m/s) x (5.0 s) = 50 meters .

===> Impact velocity = (10 m/s horizontally) + (49 m/s vertically)

   = √(10² + 49²) = 50.01 m/s arctan(10/49)

   =    50.01 m/s at 11.5° from straight down,
      away from the base of the cliff.

7 0

3 years ago

Read 2 more answers

Potassium is a crucial element for the healthy operation of the human body. Potassium occurs naturally in our environment and th

gregori [183]

Complete Question

Potassium is a crucial element for the healthy operation of the human body. Potassium occurs naturally in our environment and thus our bodies) as three isotopes: Potassium-39, Potassium-40, and Potassium-41. Their current abundances are 93.26%, 0.012% and 6.728%. A typical human body contains about 3.0 grams of Potassium per kilogram of body mass. 1. How much Potassium-40 is present in a person with a mass of 80 kg? 2. If, on average, the decay of Potassium-40 results in 1.10 MeV of energy absorbed, determine the effective dose (in Sieverts) per year due to Potassium-40 in an 80- kg body. Assume an RBE of 1.2. The half-life of Potassium-40 is $1.28 * 10^9$ years.

Answer:

The potassium-40 present in 80 kg is $Z = 0.0288 *10^{-3}\ kg$

The effective dose absorbed per year is $x = 2.06 *10^{-24}$ per year

Explanation:

From the question we are told that

The mass of potassium in 1 kg of human body is $m = 3g= \frac{3}{1000} = 3*10^{-3} \ kg$

The mass of the person is $M = 80 \ kg$

The abundance of Potassium-39 is 93.26%

The abundance of Potassium-40 is 0.012%

The abundance of Potassium-41 is 6.78 %

The energy absorbed is $E = 1.10MeV = 1.10 *10^{6} * 1.602 *10^{-19} = 1.7622*10^{-13} J$

Now 1 kg of human body contains $3.0*10^{-3}\ kg$ of Potassium

So 80 kg of human body contains k kg of Potassium

=> $k = \frac{ 80 * 3*10^{-3}}{1}$

$k = 0.240\ kg$

Now from the question potassium-40 is 0.012% of the total potassium so

Amount of potassium-40 present is mathematically represented as

$Z = \frac{0.012}{100} * 0.240$

$Z = 0.0288 *10^{-3}\ kg$

The effective dose (in Sieverts) per year due to Potassium-40 in an 80- kg body is mathematically evaluated as

$D = \frac{E}{M}$

Substituting values

$D = \frac{1.7622*10^{-13}}{80}$

$D = 2.2*10^{-15} J/kg$

Converting to Sieverts

We have

$D_s = REB * D$

$D_s = 1.2 * 2.2 *10^{-15}$

$D_s = 2.64 *10^{-15}$

So

for half-life ( $1.28 *10^9 \ years$ ) the dose is $2.64 *10^{-15}$

Then for 1 year the dose would be x

=> $x = \frac{2.64 *10^{-15}}{1.28 * 10^9}$

$x = 2.06 *10^{-24}$ per year

7 0

4 years ago

6. A man with a mass of 75 kg standing on a skateboard is holding a medicine ball that has

Nezavi [6.7K]

Answer:

Explanation:

Conservation of momentum

a) the man and skateboard move to the right.

b) His speed depends on the reference frame of the ball speed.

If the speed of the ball is 10 m/s relative to ground and the man's final speed is v, then.

(75 + 20)(0) = 20(10) + 75(v)

v = -200/75 = -2.6666...

|v| = 2.7 m/s relative to the ground

This is the likely answer they are seeking.

If the ball is thrown with a speed of 10 m/s relative to the man

(70 + 20)(0) = 20(v + 10) + 75v

20v + 200 = - 75v

200 = - 95v

v = -2.105... m/s velocity or a speed of

<em> |v| = 2.1</em> m/s relative to ground

and the ball has a velocity of 10 - 2.1 = <em>7.9 m/s </em>relative to ground.

5 0

2 years ago