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2 years ago

12

How high must you lift a 25 Newton book for it to have the same increase in potential energy as a 20 Newton book that was lifted

to 0.5 meters?

1 answer:

Annette [7]2 years ago

4 0

Given :

An object with weight 20 N was lifted to 0.5 meters.

To Find :

How high must you lift a 25 Newton book for it to have the same increase in potential energy as the given book.

Solution :

Since both have same potential energy :

$P.E_2 = P.E_1\\\\W_2h_2 = W_1h_1$

Putting all given values in above equation :

$25h_2 = 20\times 0.5\\\\h_2 = \dfrac{20\times 0.5}{25}\\\\h_2 = 0.4\ m$

Therefore, book with same potential energy is at a height of 0.4 m.

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Help me please, i need it fast

s2008m [1.1K]

Answer:

2) C. (x - 3)² + (y + 2)² = 25

5) x² + y² - 8x - 16y + 54 = 0

6) x² + y² - 10x - 12y + 36 = 0

Explanation:

2)

center of circle = 3, -2

x1, y1

end point of circle = 7, 1

x2, y2

the equation of a circle is Pythagorean theorem

x² + y² = r² (where r is the radius of a circle)

distance between points

(x2 - x1)² + (y2 - y1)² = r²

(7 - 3)² + (1 - (-2))² = r²

r² = 25

therefore the equation to the circle is

(x - 3)² + (y + 2)² = 25

=========================================

5)

write the general form of a circle with the center (4,8)

and containing the point (-1, 7)

distance between points

(x2 - x1)² + (y2 - y1)² = r²

(-1 - 4)² + (7 - 8)² = r²

r² = 26

(x - 4)² + (y - 8)² = 26

(x - 4)(x - 4) + (y - 8)(y - 8) = 26

x² - 8x + 16 + y² - 16y + 64 -26 = 0

x² + y² - 8x - 16y + 54 = 0

=========================================

6)

find the general form of a circle with center (5,6)

and tangent to the y-axis.

center (5,6)

h, k

radius = r²

r = 5

(x - h)² + (y - k)² = r²

(x - r)² + (y - k)² = r²

(x - 5)(x - 5) + (y - 6)(y - 6) = r²

x² - 10x + 25 + y² - 12y + 36 = 25

x² + y² - 10x - 12y + 36 = 0

=========================================

8 0

3 years ago

A thin uniform rod (length = 1.2 m, mass = 2.0 kg) is pivoted about a horizontal, frictionless pin through one end of the rod. (

Anika [276]

Answer:

$a=9.8 rad/s^{2}$

Explanation:

Torque, $\tau$ is given by

$\tau=Fr$ where F is force and r is perpendicular distance

$R=0.5Lcos\theta$ where $\theta$ is the angle of inclination

Torque, $\tau$ can also be found by

$\tau=Ia$ where I is moment of inertia and a is angular acceleration

Therefore, Fr=Ia and F=mg where m is mass and g is acceleration due to gravity

Making a the subject, $a=\frac {Fr}{I}=\frac {mgr}{I}$ and already I is given as

$I=\frac {mL^{2}}{3} and r is 0.5Lcos\theta$ hence

$a=\frac {0.5mgLcos\theta}{1/3 mL^{2}}$

$a=\frac {3gcos\theta}{2L}$

Taking g as 9.81, $\theta$ is given as 37 and L is 1.2

$a=\frac {3*9.81cos37}{2*1.2}=9.7932679419$

$a=9.8 rad/s^{2}$

4 0

3 years ago

Assume a reaction takes 7.5 moles of anhydrous calcium chloride and energy transfer occurs, which we record as 21.2 joules of en

OLga [1]

Answer: 2.83 J/mol

Explanation:

Heat of solution, sometimes interchangeably called enthalpy of solution, is said to be the energy released or absorbed when the solute dissolves in the solvent. A solute is that which can dissolve in a solvent, to form a solution

Given

No of moles of CaCl = 7.5 mol

Total energy used = 21.2 J

Heat of solution = q/n where

q = total energy

n = number of moles

Heat of solution = 21.2 / 7.5

Heat of solution = 2.83 J/mol

8 0

3 years ago

Read 2 more answers

The voltage ???? in a simple electrical circuit is slowly decreasing as the battery wears out. The resistance ???? is slowly inc

zimovet [89]

Answer:

The change in current at $R =456 \Omega$ is $\frac{dI}{dt} = 7.032 * 10^{-5} A/s$

Explanation:

From the question we are told that

The resistance is $R = 465 \Omega$

The current is $I = 0.09A$

The change in voltage with respect to time is $\frac{dV}{dt} = - 0.03 V/s$

The change in resistance with time is $\frac{dR}{dt} = 0.03 \Omega /s$

According to ohm's law

$V = IR$

differentiating with respect to time using chain rule

$\frac{dV}{dt} = I \frac{dR}{dt} + R * \frac{dI}{dt}$

substituting value at R = 456

$-0.0327 = 0.09 * 0.03 + 456* \frac{dI}{dt}$

$\frac{dI}{dt} = 7.032 * 10^{-5} A/s$

6 0

3 years ago

Solve 3* +5-220t = 0

slega [8]

Answer:

t = 27.5

Explanation:

$3 + 5 -220t = 0$

Well to solve for t we need to combine like terms and seperate t.

So 3+5= 8

8 - 220t = 0

We do +220 to both sides

8 = 220t

And now we divide 220 by 8 which is 27.5

Hence, t = 27.5

4 0

3 years ago