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sasho [114]
2 years ago
11

Standing on top of a building, Bob tosses a baseball straight up with an initial speed of 15 m/s. It takes 4.0 s for the ball to

hit the ground. What is the vertical distance of the building? (g = -9.8 m/s²)
Physics
1 answer:
r-ruslan [8.4K]2 years ago
5 0

Answer:

48.26 m

Explanation:

time to goes up (till stop for a while in the air - maximum height)

vt = vo + a t

0 = 15 + g . t

0 = 15 + (-9.8) . t

9.8t = 15

t = 1.531 s

so the time left to goes down is

4.0 - 1.531 = 2.469 s

height from the top of building can find it by using

vo =√(2gh)

15 = √(2)(9.8).h

15² = 19.6h

h = 225/19.6 = 11.48 m

so the distance of maximum height to the ground is

t = √(2H/g)

2.469 = √(2H/9.8)

2.469² = 2H/9.8

6.096 = 2H/9.8

2H = 6.096 x 9.8 = 59.74 m

so the vertical distance of the building (or the building height's is)

H - h = 59.74 - 11.48 = 48.26 m

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bonufazy [111]

So there is a decimal after the last zero and it looks like this 5098000. You have to move the decimal point six back to get in between the five and the zero which looks like this 5.098000 

<span>Scientific notation is the way that scientists easily handle very large numbers or very small numbers. For example, instead of writing 0.0000000056, we write 5.6 x 10^<span>9</span>.</span>

Being that we moved the decimal six places back the answer is 5.098 x 10^6

3 0
3 years ago
When you jump, you exert a pushing force against the ground. Gravity pulls you back down. Why can a person jump higher on the mo
Dennis_Churaev [7]

Answer:

This is because the force of gravity is much less on the moon than on the earth, therefore the person wont be pulled down much and will jump higher

7 0
2 years ago
Knives, axe ,blades and nails are examples of
zepelin [54]

knives, axe ,blades and nails are examples of potential energy

or sharp objects

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2 years ago
Steam in a heating system flows through tubes whose outer diameter is 5 cm and whose walls are maintained at a temperature of 13
svet-max [94.6K]

Answer:

5945.27 W per meter of tube length.

Explanation:

Let's assume that:

  • Steady operations exist;
  • The heat transfer coefficient (h) is uniform over the entire fin surfaces;
  • Thermal conductivity (k) is constant;
  • Heat transfer by radiation is negligible.

First, let's calculate the heat transfer (Q) that occurs when there's no fin in the tubes. The heat will be transferred by convection, so let's use Newton's law of cooling:

Q = A*h*(Tb - T∞)

A is the area of the section of the tube,

A = π*D*L, where D is the diameter (5 cm = 0.05 m), and L is the length. The question wants the heat by length, thus, L= 1m.

A = π*0.05*1 = 0.1571 m²

Q = 0.1571*40*(130 - 25)

Q = 659.73 W

Now, when the fin is added, the heat will be transferred by the fin by convection, and between the fin and the tube by convection, thus:

Qfin = nf*Afin*h*(Tb - T∞)

Afin = 2π*(r2² - r1²) + 2π*r2*t

r2 is the outer radius of the fin (3 cm = 0.03 m), r1 is the radius difference of the fin and the tube ( 0.03 - 0.025 = 0.005 m), and t is the thickness ( 0.001 m).

Afin = 0.006 m²

Qfin = 0.97*0.006*40*(130 - 25)

Qfin = 24.44 W

The heat transferred at the space between the fin and the tube will be:

Qspace = Aspace*h*(Tb - T∞)

Aspace = π*D*S, where D is the tube diameter and S is the space between then,

Aspace = π*0.05*0.003 = 0.0005

Qspace = 0.0005*40*(130 - 25) = 1.98 W

The total heat is the sum of them multiplied by the total number of fins,

Qtotal = 250*(24.44 + 1.98) = 6605 W

So, the increase in heat is 6605 - 659.73 = 5945.27 W per meter of tube length.

5 0
3 years ago
The kinetic energy <br> as the roller coaster goes downhil
Step2247 [10]

Answer:

Increases

Explanation:

The kinetic energy _____ (Increses)

as the roller coaster goes downhill

4 0
1 year ago
Read 2 more answers
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