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morpeh [17]
3 years ago
9

a 45kg box of books is lifted o a bookself 1.75 m above the floor. how much work was done to lift the books?

Physics
1 answer:
jekas [21]3 years ago
7 0

Answer:

770 J

Explanation:

W = PE

W = mgh

W = (45 kg) (9.8 m/s²) (1.75 m)

W = 770 J

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A tiny 0.0250 -microgram oil drop containing 15 excess electrons is suspended between to horizontally closely-spaced metal plate
qaws [65]

Answer:

(a) 12 × 10⁻³ C = 12 mC (b) The lower plate

Explanation:

Given

mass of oil drop, m = 0.025 μg =  0.025 × 10⁻⁶

radius of plates, r = 6.50 cm = 6.5 × 10⁻² m

k = 1/4πε₀ = 9.0 × 10⁹ Nm²/C²

electric charge, e= 1.6 × 10⁻¹⁹ C

charge on oil drop, q = 15e

charge on plates, Q = ?

First, we find the charge density of the plates, D = Q/A where Q = charge on plates and A = area of plates. Since the plates are circular, the area is given by A=πr² where r = radius of plates. D=Q/πr²

Also, the electric field, E between the plates is given by E = D/ε =Q/Aε = Q/ε₀πr².

The force on the oil drop due to the electric field between the plates is given by F = qE = qQ/ε₀πr².

Since the oil drop is suspended between the plates, it means that the electric force due to the field on the oil drop balances the weight of the oil drop. So, since weight of oil drop W = mg where g = 9.8 m/s². F =W (for oil drop suspension).

So, qQ/ε₀πr²=mg

So, Q=mgε₀πr²/q

From k = 1/4πε₀, ε₀=1/4πk

So, Q = mgπr²/4πkq = mgr²/4kq = (0.025 × 10⁻⁶ × 9.8 × (6.5 × 10⁻²)²)÷(4 × 9 × 10⁹ × 15 × 1.6 × 10⁻¹⁹)= 0.012 C = 12 mC

(b) The lower plate must be positive because, the direction of the electric field must be upwards, so as to balance out the weight of the oil drop so as to suspend it.

6 0
3 years ago
PLS ANSWER DUE LATER TODAY !!!
Assoli18 [71]
Magna Carta. I’m pretty sure it’s the correct answer.
4 0
3 years ago
Read 2 more answers
A box has a momentum of
Kipish [7]

Answer:

67.9 kg*m/s

Explanation:

Pi = 38 kgm/s

F = 88.3N and ∆t = 0.338s

Final momentum Pf = Pi + F∆t = 38 + (88.3)(0.338) = 38 + 29.8454

=) Pf = 67.8454 kgm/s = 67.85kg*m/s

Your answer is 67.9kg*m/s with three significant figures

hope this helps your troubles!

6 0
2 years ago
What is the speed of light in meters per second?
MAXImum [283]
The answer is approximately 2.998e+8
3 0
3 years ago
Based on the chemical equation, use the drop-down menu to choose the coefficients that will balance the chemical
MaRussiya [10]

The coefficients in order are 2, 1, 1

<h3>What is balanced chemical equation?</h3>

A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge is the same for both the reactants and the products.

In other words, the mass and the charge are balanced on both sides of the reaction.

According to the given situation,

To balance the the chemical equation,

Step 1 - Add a 2 on the Na2HPO4:

2(Na₂HPO₄)  ⇒ Na4P₂O₇ + H₂O

Step 2 -Next take count of each element on both sides to see if the 2 is balanced or not:

On the left there are 4 Na, 2 H, 2 P, and 8 O

On the right there are 4 Na, 2 H, 2 P, and 8 O

Step 3 - Now we will divide by 2

i.e. 2 NA.H. P

The coefficient of  Na is 2 , Coefficient of H is 1 and Coefficient of P is 1

Therefore,

The coefficients in order are 2, 1, 1.

Learn more about balanced chemical equation here:

brainly.com/question/15052184

#SPJ1

8 0
2 years ago
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