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3 years ago

Alfred Wegener believed that all of the continents were originally:

1 answer:

5 0

Alfred Wegener believed that all of the continents were originally attached! By looking at the map, you can see that Africa and South America look like they were once joined. This 'super continent' was known as Pangaea. He also found fossils that proved his point.
Hope this helps :)

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The gravitational force on a baseball is 1.4 N. What is its mass? Round to two decimal places.

valina [46]

Answer:

0.14 kg

Explanation:

W = mg

1.4 N = m (9.8 m/s²)

m = 0.14 kg

8 0

3 years ago

A model rocket is fired vertically upward from rest. Its acceleration for the first three seconds is a(t) = 60t at which time th

xz_007 [3.2K]

Answer:

(a) 8.4375 s

(b) 1409.06 ft

Explanation:

v’(t)=a(t)=60t therefore

$v(t)=\int 60t=60\frac {t^{2}}{2}=30t^{2}$

$s(t)=\int v=\int 30t^{2}=30\frac {t^{3}}{3}=10t^{3}$

For first three seconds

$S(3)=10*3^{3}=270$

Since motion is vertical and we take upward direction as positive, acceleration is negative hence

a(t)=-32 and $v(t)=\int -32=-32t+c$ but since at t=0 then v=270 hence c=270

-32.2t+270=0 hence

t=270/32=8.4375 s

(b)

$s(t)=-16t^{2}+270t+B$ and since s(0)=270 then

$s(t)=-16t^{2}+270t+270$

$s(8.4375)=-16(8.4375)^{2}+270(8.4375)+270\approx 1409.06 ft$

(c)

v(15)=-32(14)+270=-178 ft/s

$s(14)=-16(14)^{2}+270(14)+270=914 ft$

Average speed in the next 5 seconds becomes $\frac {-178-18}{2}=-98 ft/s and s(5)=98(5)=490 ft$

The altitude is 914-490=424 ft

$Time=\frac {424}{18}=23.6 seconds$

Time when rocket hits ground

Total time=3+14+23.6=40.55 seconds

5 0

3 years ago

Consider helium at 350 K and 0.75 m3/kg. Using Eq. 12-3, determine the change in pressure corresponding to an increase of (a) 1

Alex777 [14]

Answer:

a) $(dP)_{v} = 9.692 kPa$

b) $(dP)_{T} = -9.692 kPa$

c) dP = 0 Pa

Explanation:

The specifies equation is :

$dz = (\frac{\delta z}{\delta x}) _{y} dx + (\frac{\delta z}{\delta y}) _{x} dy$

Note that:

$dP = \frac{R}{v} dT - \frac{RT}{v^{2} } dV$

1% increase in temperature at specific volume:

$dT = \frac{0.01}{1} *350\\dT = 3.5 K$

a) Change in pressure of helium at constant volume:

$(dP)_{v} = \frac{R}{v} dT$

R = 2.0769 kJ/kg-K

dT = 3.5 K

v = 0.75 m³/kg

$(dP)_{v} = \frac{2.0769}{0.75} * 3.5\\(dP)_{v} = 9.692 kPa$

dv = (1%/100%) *0.75

dv = 0.0075 m³/kg

Change in pressure of helium at constant temperature:

$(dP)_{T} = \frac{-RT}{v^{2} } dv$

R = 2.0769 kJ/kg-K

T = 350 K

v = 0.75 m³/kg

dv = 0.0075 m³/kg

$(dP)_{T} = \frac{-(2.0769*350)}{0.75^{2} } *0.0075\\(dP)_{T} = -9.692 kPa$

c) The change in pressure of helium :

$dP = (dP)_{v} + (dP)_{T}$

dP = 9.692 - 9.692

dP = 0

5 0

4 years ago

Relying on windows and building materials to capture incoming solar radiation WITHOUT distributing that energy is called:

eimsori [14]

The best and most correct answer among the choices provided by your question is the second choice or letter B.

<span>Relying on windows and building materials to capture incoming solar radiation WITHOUT distributing that energy is called: passive solar heating.</span>

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

5 0

3 years ago

Read 2 more answers

Density problems brainless anwser to first person who does it

Aleks04 [339]

<u>First question:</u>

Density = $\frac{mass}{volume}$

Mass = density × volume

The density of the cube is 1.2g/cm³

The volume of the cube is given by side × side × side:

Volume = 7cm × 7cm × 7cm = 347cm³

Mass = 1.2g/cm³ × 343cm³ = 411.6g

*Hint: Just apply the formula Density = $\frac{mass}{volume}$ to solve the next questions.

4 0

3 years ago