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3 years ago

13

A child riding a bicycle at 5 meters per seconds accelerates at 2.0 meters per second for 4.0 seconds. What is the child's speed

at the end of this 4.0 second interval

1 answer:

slega [8]3 years ago

5 0

Explanation:

Using Kinematics,

We have v = u + at.

=> v = (5m/s) + (2.0m/s²)(4.0s)

=> v = 13m/s.

Hence the child's speed is now 13m/s.

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From the things on that list, the copper wire has the least resistance ... unless it happens to be several miles long.

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The system below uses massless pulleys and ropes. The coefficient of friction is μ. Assume that M1 and M2 are sliding. Gravity i

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Explanation:

Using Newtons second law on each block

F = m*a

Block 1

$T_{1} - u*g*M_{1} = M_{1} *a \\\\T_{1} = M_{1}*(a + u*g) ... Eq1$

Block 2

$T_{2} - u*g*M_{2} = M_{2} *a \\\\T_{2} = M_{2}*(a + u*g) ... Eq2$

Block 3

$- (T_{1} + T_{2} ) + g*M_{3} = M_{3} *a \\\\T_{1} + T_{2} = M_{3}*( -a + g) ... Eq3$

Solving Eq1,2,3 simultaneously

Divide 1 and 2

$\frac{T_{1} }{T_{2}} = \frac{M_{1}*(a+u*g)}{M_{2}*(a+u*g)} \\\\\frac{T_{1} }{T_{2}} = \frac{M_{1} }{M_{2} }\\\\ T_{1} = \frac{M_{1} *T_{2} }{M_{2} } .... Eq4$

Put Eq 4 into Eq3

$T_{2} = \frac{M_{3}*(g-a) }{1+\frac{M_{1} }{M_{2} } } ...Eq5$

Put Eq 5 into Eq2 and solve for a

$a = \frac{M_{3}*g -u*g*(M_{1} + M_{2}) }{M_{1} + M_{2} + M_{3} } .... Eq6$

Substitute back in Eq2 and use Eq4 and solve for T2 & T1

$T_{2} = M_{2}*M_{3}*g*(\frac{1-u}{M_{1} + M_{2}+M_{3}})\\\\T_{1} = M_{1}*M_{3}*g*(\frac{1-u}{M_{1} + M_{2}+M_{3}})\\\\$

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4 years ago

A sample with a path length of 1 cm absorbs 99.0% of the incident light at a wavelength of 274 nm, measured with respect to an a

Ksju [112]

Answer:

17. NADH has a molar extinction coefficient of 6200 M2 cm at 340 nm. Calculate the molar concentration of NADH required to obtain an absorbance of 0.1 at 340 nm in a 1-cm path length cuvette. 18. A sample with a path length of 1 cm absorbs 99.0% of the incident light at a wavelength of 274 nm, measured with respect to an appropriate solvent blank. Tyrosine is known to be the only chromophore present in the sample that has significant absorption at 274 nm. Calculate the molar concentration of tyrosine in the sample.

Explanation:

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3 years ago

Shrinking Loop. A circular loop of flexible iron wire has an initial circumference of 167 cm , but its circumference is decreasi

PSYCHO15rus [73]

Answer:

a) fem = - 0.0103 V, b) the applied field is in a vertical upward direction, the induced current is clockwise.

Explanation:

a) For this exercise we use Faraday's law

fem = $- \frac{d \phi}{dty}$

the magnetic flux is

Ф = B. A = B A cos θ

The bold letters indicate vectors, in this case the direction of the magnetic field and the normal to the circumference is parallel therefore the angle is zero and the cos 0 = 1

fem = - B dA / dt

the area of a circle is

A = π r²

l

et's perform the derivative

dA / dt =π 2r $\frac{dr}{dt}$

we substitute

fem = - B 2π r $\frac{dr}{dt}$

the circumference of a circle is

L = 2π r

we substitute

fem = - B L ( L )

fem =

Let's find the circumference for the 9 s, let's use a direct rule of proportions

If the circumference changes 13cm at t = 1. how much does it change at t=9s

ΔL = 13cm (9s / 1s) = 117cm

the circumference that is

L = Lo - ΔL

L = 167 - 117

L = 50 cm

let's reduce all magnitudes to the SI system

L = 0.50 m

= 0.130 m / s

calculate us

fem = - 1.00 0.50 0.130

fem = - 0.0103 V

b) the electromotive force induced in the opposite direction to the change of the radius and is decreasing with time, the current follows the direction of the decreased voltage therefore the current is induced in the opposite direction to the change of the magnetic flux.

If the applied field is in a vertical upward direction, the induced current is clockwise.

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3 years ago

A device for acclimating military pilots to the high accelerations they must experience consists of a horizontal beam that rotat

slava [35]

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Explanation:

The data we have is:

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And we can write the velocity as:

v = w*r where r is the radius of the circle, and w is the angular frequency.

w = 2pi*f

where f is the "normal" frequency.

So we have:

A = (v^2)/r = (r*w)^2/r = r*w^2

We can replace the values and find w.

27.9m/s^2 = 5.21m*w^2

√(27.9/5.21) = w = 2.31 rad/s

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3 years ago