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Bogdan [553]
3 years ago
9

A boy jumps from rest, straight down from the top of a cliff. He falls halfway down to the water below in 0.866 s. How much time

passes during his entire trip from the top down to the water? Ignore air resistance.
Physics
1 answer:
Iteru [2.4K]3 years ago
7 0
<h2>Entire trip takes 1.22 seconds.</h2>

Explanation:

We have equation of motion s = ut + 0.5 at²

        Initial velocity, u = 0 m/s

        Acceleration, a = 9.81 m/s²  

        Time, t = 0.866 s      

     Substituting

                      s = ut + 0.5 at²

                      s = 0 x 0.866 + 0.5 x 9.81 x 0.866²

                      s = 3.68 m

      Halfway is 3.68 m

Total height = 2 x 3.68 = 7.36 m

We have equation of motion s = ut + 0.5 at²

        Initial velocity, u = 0 m/s

        Acceleration, a = 9.81 m/s²  

        Time, t = ?

        Displacement, s  = 7.36 m

     Substituting

                      s = ut + 0.5 at²

                      7.36 = 0 x t + 0.5 x 9.81 x t²

                      t = 1.22 s

Entire trip takes 1.22 seconds.

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A cyclist overcomes a resistive force of 30 N in order to cycle 30 m. It takes her 6 seconds to cycle this distance. Calculate t
zmey [24]

Answer:

Power = 15[W]

Explanation:

This problem can be solved using the work definition.

Work is equal to the product of the force by the distance, for this problem we have:

F = force = 30 [N]

d = distance = 30 [m]

w = work = F * d = 30*30 = 900 [J], "units in joules"

The power is defined as the work done in an interval of time.

P = w / t

where:

t = time [s]

therefore

P = w / t

P = 900 / 6

P = 150 [W] "units in watts"

6 0
3 years ago
Why is "Creation-Science" not considered true science?
jarptica [38.1K]
My answer would be because it is based on the belief that God created the Earth and cannot be proven by science but requires someone to believe that it is true
8 0
3 years ago
Read 2 more answers
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Diano4ka-milaya [45]
I think it's B because when you graph you do see the relationship between the dependent and independent variable
8 0
3 years ago
Identify the physical mechanism that causes turbulent thermal conductivity.
myrzilka [38]

Answer:

Option A is correct.

Eddies due to enhanced mixing of fluid

Explanation:

Turbulent thermal conductivity is thermal conductivity that arises from the turbulent flow of fluids. It comes into play when a particukar fluid moves into turbulent regiom of flow where flow is no longer orderly and streamlines aren't discernable with the fluid layers all warping into one another forming vortices.

It is represented as K and is shown mathematically through the heat flux at turbulent flow

q = vCρT' = - K (∂T/∂y)

where

K = turbulent thermal conductivity

T' = the eddy temperature relative to the mean value,

C = Heat capacity the fluid

q = the rate of thermal energy transport by turbulent eddies.

The physical mechanism that cause turbulent thermal conductivity are similar to the causes of turbulent flow of fluids.

This includes sharp changes in fluid pressure and velocity of flow which is evident in eddies that come about in the enhanced mixing of fluids.

Hope this Helps!!!

5 0
3 years ago
A bowler throws a bowling ball of radius R = 11 cm down the lane with initial speed v₀ = 7.5 m/s. The ball is thrown in such a w
salantis [7]

Answer:

a) t = 0.74s

b) D = 4.76m

c) Vf = 5.35m/s

Explanation:

The ball starts rolling when Vf = ωf*R.

We know that:

Vf = Vo - a*t

ωf = ωo + α*t

With a sum of forces on the ball:

Ff = m*a

\mu*N = m*a

\mu*m*g = m*a

a=\mu*g=2.9m/s^2

With a sum of torque on the ball:

Ff*R = I*\alpha

\mu*m*g*R = 2/5*m*R^2*\alpha

\alpha=5/2*\mu*g/R=65.9rad/s^2

Replacing both accelerations:

Vo - a*t=\alpha*t*R

7.5 - 2.9*t=65.9*t*0.11

t=0.74s

The distance will be:

D = Vo*t-1/2*a*t^2

D = 4.76m

Final velocity:

Vf=Vo-a*t

Vf=5.35m/s

7 0
3 years ago
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