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2 years ago

11

A boy throws a steel ball straight up. consider the motion of the ball only after it has left the boy's hand but before it touch

es the ground, and assume that forces exerted by the air are negligible. for these conditions, the force(s acting on the ball is (are

2 answers:

kap26 [50]2 years ago

3 0

The forces acting on the ball, aside from air friction, would be the force exerted on the ball by the boy when he threw it up, and gravity working against the motion of the ball

sweet-ann [11.9K]2 years ago

3 0

The gravity is working against the movement of the ball

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What does the Pauli exclusion principle state? . . A.Electrons will be added to an atom at the lowest possible level or sublevel

BARSIC [14]

The Pauli exclusion principle state that : D. Two electrons occupy the same orbital only if they have opposite spins

This happen because he stated that in an atom or molecule, two electrons CANNOT have same four electronic quantum numbers

hope this helps

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3 years ago

A parked car begins to roll down a hill, what can you conclude from that observation?

Fynjy0 [20]

Answer:

its The rolling friction is greater than the force of the car’s weight against the hill.

and A force was required to start the car rolling.

Explanation:

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2 years ago

Two friends, Al and Jo, have a combined mass of 195 kg. At the ice skating rink, they stand close together on skates, at rest an

ddd [48]

Answer:

Al's mass is 102.92 kg

Explanation:

As there are no external forces in the horizontal direction, the horizontal net force must be zero:

$F_{net} = 0$

As the force is the derivative in time of the momentum, this means that the horizontal momentum is constant:

$F_{net} = \frac{dp_{horizontal}}{dt} = 0$

$p_{horizontal_i }= p_{horizontal_f}$

where the suffix i and f means initial and final respectively.

The initial momentum will be:

$p_{horizontal_}i = m_{Al} \ v_{Al_i} + m_{Jo} \ v_{Jo_i}$

But, as they are at rest, initially

$p_{horizontal_i} = m_{Al} * 0 + m_{Jo} * 0$

$p_{horizontal_i} = 0$

So, this means:

$p_{horizontal_f} = m_{Al} \ v_{Al_f} + m_{Jo} \ v_{Jo_f} = 0$

We know that the have an combined mass of 195 kg:

$m_{total} = m_{Al} + m_{Jo} = 195 \ kg$ .

so:

$m_{Jo} = 195 \ kg - m_{Al}$ .

$m_{Al} \ v_{Al_f} + (195 \ kg - m_{Al}) \ v_{Jo_f} = 0$

$m_{Al} \ v_{Al_f} - m_{Al} \ v_{Jo_f}= - 195 \ kg \ v_{Jo_f}$

$m_{Al} \ (v_{Al_f} - v_{Jo_f})= - 195 \ kg \ v_{Jo_f}$

$m_{Al} = \frac{ - 195 \ kg \ v_{Jo_f} } { v_{Al_f} - v_{Jo_f} }$

$m_{Al} = \frac{195 \ kg \ v_{Jo_f} } { v_{Jo_f} - v_{Al_f} }$

Now, we can use the values:

$v_{Al_f}= 10.2 \frac{m}{s}$

$v_{Jo_f}= - 11.4 \frac{m}{s}$

where the minus sign appears as they are moving at opposite directions

$m_{Al} = \frac{195 \ kg ( - 11.4 \frac{m}{s} ) } { (- 11.4 \frac{m}{s}) - 10.2 \frac{m}{s} }$

$m_{Al} = 102.92 \ kg$

and this is the Al's mass.

5 0

2 years ago

Which of the following accurately describes the differences between the SI and English systems of measurement?

Digiron [165]

The best answer is D. The SI system, which is based on the metric system, has been more widely adopted than the English system, which is harder to use. In order to standardize measurements, the International System of Units or the SI units are commonly used around the world since they are more easy to understand and compare than the English unit.

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3 years ago

Read 2 more answers

Consider steady heat transfer between two large parallel plates at constant temperatures of T1 = 210 K and T2 = 150 K that are L

snow_lady [41]

Answer:

$Q=81.56\ W/m^2$

Explanation:

Given that

$T_1= 210 K$

$T_2= 150 K$

Emissivity of surfaces(∈) = 1

We know that heat transfer between two surfaces due to radiation ,when both surfaces are black bodies

$Q=\sigma (T_1^4-T_2^4)\ W/m^2$

So now by putting the values

$Q=\sigma (T_1^4-T_2^4)\ W/m^2$

$Q=5.67\times 10^{-8}(210^4-150^4)\ W/m^2$

$Q=81.56\ W/m^2$

So rate of heat transfer per unit area

$Q=81.56\ W/m^2$

8 0

3 years ago