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Marta_Voda [28]
3 years ago
12

A ball is thrown down vertically with an initial speed of 31 ft/s from a height of 40 ft. (a) What is its speed just before it s

trikes the ground? (b) How long does the ball take to reach the ground? What would be the answers to (c) part a and (d) part b if the ball were thrown upward from the same height and with the same initial speed ? Before solving any equations, decide whether the answers to (c) and (d) should be greater than, less than, or the same as in (a) and (b).
Physics
1 answer:
ICE Princess25 [194]3 years ago
5 0

Answer:

a. 41.96ft/s

b. 1.096s

Explanation:

a. v²=u²+2gs

v²=31²+2×10×40

V=41.96ft/s

b. t=(v-u) /g

t=(41.96-31)/10

t=1.096s

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AURORKA [14]
The measurement of sound is in decibels.
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A container is filled to a depth of 19.0 cm with water. On top of the water floats a 31.0-cm-thick layer of oil with specific gr
IceJOKER [234]

Answer:

Absolute pressure of the oil will be 102822.8 Pa  

Explanation:

We have given height h = 31 cm = 0.31 m

Acceleration due to gravity g=9.8m/sec^2

Specific gravity of oil = 0.600

So density of oil \rho =0.6\times 1000=600kg/m^3

We know that absolute pressure is given by P=P_0+\rho gh, here P_0=1.01\times 10^5Pa

So absolute pressure will be equal to P=1.01\times 10^5+600\times 9.8\times 0.31=102822.8Pa

So absolute pressure of the oil will be 102822.8 Pa

6 0
3 years ago
a constant force acts on an object of mass 10 kg for a duration of 2 seconds it increases the object velocity from 4metre per se
inn [45]

Answer:

F=ma

a=v/t

a=vf-vi/t

a=8-4/2

a=4÷2

a=2msec*2

F=10×2

F=20N

3 0
2 years ago
Consider a vortex filament of strength Γ in the shape of a closed circular loop of radius R. Consider also a straight line throu
Sedbober [7]

Answer:

\vec{V} = \frac{\Gamma}{2R}\vec{A}

Explanation:

We define our values according to the text,

R= Radius

\vec{V} =Velocity

\Gamma =Strenght of the vortex filament

From this and in a vectorial way we express an elemental lenght of this filmaent as \vec{dl}. So,

\vec{dl}x\vec{r} = R*dl*\vec{A}

Where \vec{A} imply a vector acting perpendicular to both vectors.

Applying Biot-Savart law, we have,

\vec{V} =\frac{\Gamma}{4\pi}\int\frac{\vec{dl}x\vec{r}}{r^3}

Substituting the preoviusly equation obtained,

\vec{V} = \frac{\Gamma}{4\pi}\int\frac{R*dl*\vec{A}}{R^3}

\vec{V} = \frac{\Gamma}{4\pi R^2}\int^{2\pi R}_0 dl*\vec{A}

\vec{V} = \frac{\Gamma(2\pi R \vec{A})}{4\pi R^2}

So we can express the velocity induced is,

\vec{V} = \frac{\Gamma}{2R}\vec{A}

6 0
3 years ago
A car moving at 10 m/s crashes into a large bush and stops in 1.3 m. Using the Work-Energy theorem, calculate the average force
ad-work [718]

Answer:

The magnitude of the average force the seat belt exerts on the passenger is 2692.3 N.

It takes 0.26 s to bring the passenger in the car to a halt.

Explanation:

Hi there!

The negative work (W) needed to bring a moving object to stop is equal to its kinetic energy (KE):

W = KE

F · s = 1/2 · m · v²

Where:

F = applied force on the passenger.

s = displacement of the passenger.

m = mass of the passenger.

v = velocity of the passenger.

Solving the equation for F:

F = 1/2 · m · v² / s

Replacing with the data:

F = 1/2 · 70 kg · (10 m/s)² / 1.3 m

F = 2692.3 N

The magnitude of the average force the seat belt exerts on the passenger is 2692.3 N.

According to the second law of Newton:

F = m · a

Where "a" is the acceleration of the passenger.

We also know from kinematics that the velocity of an object can ve calculated as follows:

v = v0 + a · t

Where:

v = velocity of the passenger at time t.

v0 = initial velocity.

t = time.

a = acceleration.

When the passenger stops, its velocity is zero. So replacing a = F/m, let´s solve the equation for the time it takes the passenger to stop:

v = v0 + a · t

0 = 10 m/s + (-2692.3 N/ 70 kg) · t

-10 m/s / (-2692.3 N/ 70 kg)  = t

t =0.26 s

It takes 0.26 s to bring the passenger in the car to a halt.

5 0
3 years ago
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