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3 years ago

a bullet is fired upwards with the initial velocity of 250m/s. determine the time taken to reach the maximum height

2 answers:

8 0

The final velocity is 0 and the acceleration is gravity. Vf=Vi+at because gravity opposes the motion it will be -g
0=250-gt
gt=250 ....g=10
t=25sec

Rainbow [258]3 years ago

7 0

Using:

v = u - gt.

Where v = final velocity in m/s, u = initial velocity in m/s, g = acceleration due to gravity in m/s², t = time in s.

At maximum height the final velocity v = 0 m/s. u = 250 m/s

v = u - gt.

0 = u - gt.

gt = u

t = u / g g ≈ 9.8 m/s²

t ≈ 250 / 9.8

t ≈ 25.51

Time to reach maximum height is ≈ 25.51 seconds.

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Calculate the change in entropy when 1.00 kg of water at 100 âˆ˜c is vaporized and converted to steam at 100 âˆ˜c. Assume that t

pickupchik [31]

Answer:6.04 kJ/K

Explanation:

Given

mass of water $m=1 kg$

Latent heat of vaporization is $L=2256\times 10^{3} J/kg$

entropy at constant temperature is given by

$\Delta S=\frac{Q}{T_0}$

$Q=m\times L$

$Q=1\times 2256\times 10^3$

$\Delta s=\frac{2256\times 10^3}{100+273}$

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4 years ago

If you were to measure the width of your lab manual with a meter stick, and then the length (roughly 50% longer), by what fracti

Leona [35]

Answer:

Explanation:

a ) Let breadth be L , then length will be 1.5 L

Since it is a meter scale , the least count is 1 m.m. So

maximum possible error in a measurement is 1 mm.

In both the measurement of length and breadth , absolute

uncertainty will be 1mm.

Hence there is no difference in absolute uncertainty of their measurement.

b ) percent uncertainty in the measurement of length

$\frac{1 mm}{1.5L\times1000} \times100$

= 1 / 15L%

percent uncertainty in the measurement of breadth

$\frac{1 mm}{L\times1000} \times100$

1 / 10L%

In breadth it will be higher by

( 1/10L - 1/15L)/ 1/10L

= 1/3

c ) Uncertainty in the measurement of R= 1 %

Area A = π R²

ΔA/A X100 = 2 X ΔR/R X 100

Percentage uncertainty in A = 2 X percentage uncertainty in R

= 2 X 1

=2 %

Therefore percentage accuracy in the calculation of area

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3 years ago

The trunk of a elephant may extend up to 2.2 m. It acts much like an organ pipe only open at one end when the elephant blows air

Talja [164]

Answer:

1) f = 38.63 Hz , 2) f = 115.9 Hz

Explanation:

The elephant's trunk can be approximated by a tube with a closed end, in pipes the closed ends correspond to nodes and the open ends to antinodes or bellies.

The expression for the wavelengths of this system is

4L = n λ

n = 1, 3, 5, 7 ...

also let's use the relationship between frequency and wavelength and wave speed

v = λ f

f = v / λ

f = v n / 4L

f = v / 4L n

1) the fundamental frequency occurs for n = 1

f = 340/4 2.2 1

f = 38.63 Hz

2) The first harmonic

n = 3

f = 340/4 2.2 3

f = 115.9 Hz

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3 years ago

Determine the angle between the directions of vector a = 3.00i 1.00j and vector b = 1.00i 3.00j .

Katena32 [7]

The angle between the two vectors is 126° 52' 11".

The given parameters;

vector A = 3.00i + 1.00j

vector B = 1.00i + 3.00j

The angle between the two vectors is calculated as follows;

$cos \theta = \frac{A.B}{|A|.|B|}$

The dot product of vectors A and B is calculated as;

A.B = ( 3i + 1j ) . ( 1i +3j )

= ( 3 × 1 ) + ( 1 × 3 )

= 3 + 3

= 6

The magnitude of vectors A and B is calculated as;

|A| = $\sqrt[]{3^2 + 1^2} = \sqrt[]{10} \\$

|B| = $\sqrt[]{1^2 + 3^2} = \sqrt[]{10} \\$

The angle between in two vectors is calculated as;

$Cos \theta = \frac{6}{\sqrt[]{10}\sqrt[]{10} } \\\\Cos \theta = \frac{6}{\ 10 }\\\\Cos \theta = 0.6\\\\\theta = cos^-^1 (0.6)\\\\\theta = 126\\$

Therefore, the angle between the two vectors is 126° 52' 11".

Learn more about vectors here:

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Answer:

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3 years ago