For a particle undergoing free-fall acceleration, the acceleration vs. time graph is

A&P I need helppp <br> plspls

katrin2010 [14]

Answer:

c

Explanation:

6 0

3 years ago

What happens to the volume the gas occupies when the pressure on a gas increases?

taurus [48]

Each time they collide with the walls they exert a force on them. More collisions mean more force, so the pressure will increase. When the volume decreases, the pressure increases. This shows that the pressure of a gas is inversely proportional to its volume.

8 0

3 years ago

Read 2 more answers

Some kids are playing by rolling a skateboard across level ground beside a 0.75 m high wall. The goal is to drop from the wall v

lys-0071 [83]

Answer:

The speed of the kid and the skateboard together is 0.723 m/s

Explanation:

Let the mass of the kid be $m_{k} = 45 kg$

Let the mass of the skateboard be $m_{s} = 4,5 kg$

The initial speed of the skateboard, $v_{s} = 8 m/s$

The initial horizontal speed of the boy as he jumps on the skateboard, $v_{k} = 0 m/s$

Let the speed of the kid and the skateboard together be v

According to the principle of conservation of momentum:

$m_{k} v_{k} + m_{s} v_{s} = (m_{k} + m_{s}) v$

Substituting the appropriate values into the given equation

$(45*0) + (4.5*8) = (45 + 4.8) v$

36 = 49.8 v

v = 36/49.8

v = 0.723 m/s

7 0

4 years ago

Astronomers can now report that active star formation was going on at a time when the universe was only 20% as old as it is toda

disa [49]

Answer:

First, as you may know, the light travels at a given velocity.

In vaccum, this velocity is c = 3x10^8 m/s.

And we know that:

distance = velocity*time

Now, if some object (like a star ) is really far away, the light that comes from that star may take years to reach the Earth.

This means that the images that the astronomers see today, actually happened years and years ago (So the night sky is like a picture of the "past" of the universe)

Also, for example, if an astronomer sees some particular thing, he can apply a model (a "simplification" of some phenomena that is used to simplify it an explain it) and with the model, the scientist can infer the information of the given thing some time before it was seen.

8 0

3 years ago

A 4.45 kg block of ice at 0.00 ?c falls into the ocean and melts. the average temperature of the ocean is 3.70 ?c, including all

rodikova [14]

The ocean does not change temperature but it does lose some entropy ( he gives heat to melt the ice and to warm it to 3.70° C ).
I ) For the ice:
1 ) For melting the ice:
Q = m · Lf = 4.45 kg · 334 · 10³ J/kg = 1,486,300 J
Δ S = Q / T = 1,486,300 J / 273.15 K = 5.441 · 10³ J/K.
2 ) To warm the melted ice to 3.70° C:
Q = m c Δ T = 4.45 kg · 4,190 J / kgK · 3.70 K = 68,988.35 J
Δ S = m c ln( T2/ T1 ) = 4.45 kg · 4,190 J/kgK · ln ( 276.85 / 273.15 ) =
= 18,645.5 · ln ( 1.01354 ) = 18.645.5 · 0.013454 = 250.8692 J/K
II ) For the ocean:
Δ S = Q / T = ( - 68,988.35 + 1,486,300 ) / 276.85 = - 5,617.8 J/K
The net entropy change:
Δ S = ΔS ice + ΔS ocean = 5,441.1 + 250.8692 - 5,617.8 = 74.1692 J/K
Answer: 74 J/K.

4 0

3 years ago