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3 years ago

Which of the following is an example of acceleration? Select one:

1 answer:

8 0

Acceleration' is any change in the speed or direction of motion. we can look through the choices:
A). /
B). No. Neither speed nor direction changed.
C). /
D). Yes. The boy's direction changed.

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a wire of a certain material has resistance r and diameter d a second wire of the same material and length is found to have resi

777dan777 [17]

Answer:

<h2>d₂ = 3d</h2><h2>The diameter of the second wire is 3 times that of the initial wire.</h2>

Explanation:

Using the formula for calculating the resistivity of an object to find the diameter.

Resistivity P = RA/L

R is the resistance of the material

A is the cross sectional area

L is the length of the material

Since A = πd²/4

P = R( πd²/4)/L

P = Rπd²/4L ... 1

If the second wire of the same material and length is found to have resistance R/9, the resistivity of the second material will be;

P₂ = (R/9)A₂/L₂

P₂ = (R/9)(πd₂²/4)/L₂

P₂ = (Rπd₂²/36)/L₂

P₂ = (Rπd₂²)/36L₂

Since the length and resistivity are the same;

P = P₂ and L =L₂

Equating 1 and 2;

Rπd²/4L = (Rπd₂²)/36L₂

Rπd²/4L = (Rπd₂²)/36L

d² = d₂²/9

d₂² = 9d²

Taking the square root of both sides;

√d₂² = √9d²

d₂ = 3d

Therefore the diameter of the second wire is 3 times that of the initial wire

5 0

4 years ago

What do understand by the efficiency of a machine? By using a block and tackel a man can raise a load of 720 N by an effort of 1

motikmotik

Answer:

Efficiency of a machine is how well the machine works and what the machine is capable of doing.

Mechanical advantage=Load/Effort.

720/180=4

6 0

3 years ago

A point moves on the x-axis in such a way that its velocity at time t (t > 0) is given by v=ln t/t . At what value of t does

Olenka [21]

Answer:

Explanation:

Given

Velocity of point is given by $v=\frac{\ln t}{t}$

To get maximum or minimum velocity differentiate v w.r.t t

$\frac{\mathrm{d} v}{\mathrm{d} t}=\frac{\frac{1}{t}\times t-1\times \ln(t)}{t^2}$

so $1-\ln (t)$ should be equal to zero

$\ln (t)=1$

$t=e$

i.e. $t=2.718\ s$

5 0

4 years ago

The equation shows neutralization of an acid and a base to produce a salt and water.

Lyrx [107]

This equation will be balanced if the x is a 2 because there are two sodiums on the reactants sides so there must be two sodiums on the products side

Hope this helps

7 0

3 years ago

Read 2 more answers

I need help asap pls

tigry1 [53]

no.9 indeed all matters are made out of atoms which is smaller than protons and neutrons

6 0

3 years ago