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3 years ago

PLEASE HELP ME WITH THOSE TWO QUESTIONS

Physics

1 answer:

Korolek [52]3 years ago

6 0

Answer:

(a) 0.014 A

(b) 2 V

Explanation:

(a) Applying

V = IR'...................... Equation 1

Where V = Voltge, I = current, R = total resistance.

make I the subject of the equation

I = V/R'................... Equation 2

From the question,

Given: V = 12 V, R' = (122+232+500) ohms (The resistance are connected in series) = 854 ohms

Substitute these values into equation 2

I = 12/854

I = 0.014 A

(b) Applying

V' = V(R₁)/(R₁+R₂+R₃)...................... Equation 3

Where V' = Voltage across the 100 ohms resistor.

From the question,

V = 12V, R₁ = 100 ohm, R₂ = 200 ohm, R₃ = 300 ohm.

Substitute these values into equation 3

V' = (12×100)/(100+200+300)

V' = 1200/600

V' = 2 V

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1. It takes a 25 N force to push a 250 N box across the floor.

Fed [463]

Answer:

A:- 50 J

B:- 500 J

Explanation:

a) Given that a 25 N force is applied to move the box. Also the floor is having friction surface.

So in order to move the box, the floor should have friction of atleast 25 N.

∴ friction = 25 N

Work done = force * displacement of box

Given, the box is moved 2 m across the floor

So, Work done = friction * 2 m

= 25 * 2

= 50 J

b) Given, the box is having weight of 250 N weight

Gravitational force is acting on the box which is equal to (mass * gravity)

∴ Force = 250 N

The box is lifted 2 m above the floor.

So, displacement = 2 m

Work done = force * displacement of box

Work done = 250 * 2

= 500 J

5 0

3 years ago

Rudy plans to conduct an experiment using three rosebushes of the same variety and size. His hypothesis is that the plant

Gala2k [10]

Answer: B) He has too many independent variables.

Explanation: Nothing in the experiment is a constant or being measured.

5 0

3 years ago

a box has a length of .5 m and a width of .1m. if the box exerts a force of 10 N on the floor, what is the pressure of the box o

faust18 [17]

Answer:

The pressure of the box on the floor is 200 Pa

Explanation:

Given,

Length of the box=0.5m

Width of the box= 0.1m

∴Area of the box, A= (0.5 X 0.1) sq.m

= 0.05 sq.m

We know,

Pressure, P= F/A

= 10/0.05 Pa

= 200 Pa

∴The pressure of the box on the floor is 200 Pa

4 0

2 years ago

Find the useful power output (in W) of an elevator motor that lifts a 2600 kg load a height of 30.0 m in 12.0 s, if it also incr

Annette [7]

Answer:

P = 251,916.667 W

Cost = 2,267.25 cents

Explanation:

To solve this question we will use the Work Energy Theorem, which is

$W = dP + dK\\$

Where

$dP$ = Change in Potential Energy

$dK$ = Change in Kinetic Energy

Change in Potential Energy

$P_{i} = mgh_{i}\\ P_{f} = mgh_{f}$

Where

$P_{i}$ = Initial Potential Energy

$P_{f}$ = Final Potential Energy

$m$ = Mass of System = 10,000 kg

$g$ = Acceleration due to gravity = 9.81 m/s

$h_{i}$ = Initial Height = 0

$h_{f}$ = Final Height = 30 m

Inputting the values we get the answer for $dP$

$dP = P_{f} - P_{i}\\dP= mgh_{f} - mgh_{i}\\ dP= 10000(9.81)(30) - 0\\ dP= 2943000$

Change in Kinetic Energy

$K_{i} = \frac{1}{2} mv_{i} ^2\\ K_{f} = \frac{1}{2} mv_{f} ^2$

Where

$K_{i}$ = Initial Kinetic Energy

$K_{f}$ = Final Kinetic Energy

$m$ = Mass of System = 10,000 kg

$g$ = Acceleration due to gravity = 9.81 m/s

$v_{i}$ = Initial Velocity = 0 m/2

$v_{f}$ = Final Velocity = 4 m/s

Inputting the values we get the answer for $dK$

$dK = K_{f} - K_{i}\\ dK = \frac{1}{2} mv_{f} ^2 - \frac{1}{2} mv_{i} ^2\\ dK = \frac{1}{2} (10000)(4)^2 - 0 \\ dK = 80000$

Total Work

$W = dP + dK\\$

Inputting the values

$W = 2943000 + 80000$

$W = 3,023,000$

a) Finding the useful Power Output

$P = \frac{W}{t}$

Where

$P$ = Power Output

$W$ = Work Done = 3,023,000J

$t$ = Time = 12s

Inputting the values

$P = \frac{3,023,000}{12}\\ P = 251,916.667$

P = 251,916.667 W

b) Finding the Total Cost

Cost = $0.0900 x P/1000

Cost = $0.0900 x (251,916.667/1000)

Cost = $22.67 or 2,267.25 cents

4 0

4 years ago

Work is done on an object when

liubo4ka [24]

Answer:

Incomplete question but the closest ans is

A) The displacement is not zero

Explanation:

For work to be done, the direction of force has to be parallel to or in the same direction as the displacement, this can then be calculated by

$W=Fs \ cos$ θ

Where θ is the angle between direction of force and direction of displacement

By this equation,

if Force is zero, W is zero

if displacement is zero, W is zero

if force and displacement are perpendicular θ=90, cosθ = 0

So A is the cloest choices

6 0

3 years ago