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3 years ago

Question 3 (5 points)

Physics

1 answer:

Elan Coil [88]3 years ago

7 0

True: when there is an angle between force and displacement, $W=Fd cos \theta$

Explanation:

The work done by a force when pushing/pulling an object is given by the equation

$W=Fd cos \theta$

where

F is the magnitude of the force

d is the displacement of the object

$\theta$ is the angle between the direction of the force and of the displacement

We have two extreme cases:

- When the force is parallel to the displacement, then $\theta=0^{\circ}$ and $cos \theta = 1$ , so the work done is maximum and simply becomes

$W=Fd$

- When the force is perpendicular to the displacement, then $\theta=90^{\circ}$ and $cos \theta =0$ , so the work done is zero.

Learn more about work:

brainly.com/question/6763771

brainly.com/question/6443626

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A person wants to lose weight by "pumping iron". The person lifts an 80 kg weight 1 meter. How many times must this weight be li

statuscvo [17]

Answer:

37357 sec

or 622 min

or 10.4 hrs

Explanation:

GIVEN DATA:

Lifting weight 80 kg

1 cal = 4184 J

from information given in question we have

one lb fat consist of 3500 calories = 3500 x 4184 J

= 14.644 x 10^6 J

Energy burns in 1 lift = m g h

= 80 x 9.8 x 1 = 784 J

lifts required $= \frac{(14.644 x 10^6)}{784}$

= 18679

from the question,

1 lift in 2 sec.

so, total time = 18679 x 2 = 37357 sec

or 622 min

or 10.4 hrs

3 0

3 years ago

When is the force on a current-carrying wire in a magnetic field at its strongest?

Hitman42 [59]

The forces on a current-carrying wire in a magnetic field are at their strongest when the current is at a 90-degree angle to the field. Option D is correct.

<h3>What is a magnetic field?</h3>

It is the type of field where the magnetic force is obtained. The magnetic force is obtained by the field felt around a moving electric charge.

The complete question is;

"When is the force on a current-carrying wire in a magnetic field at its strongest?

-when the current is at a 0-degree angle to the field

-when the current is at a 30-degree angle to the field

-when the current is at a 45-degree angle to the field

-when the current is at a 90-degree angle to the field"

The magnetic force is found as;

F=BILSINΘ

Where,

Magnetic Field, B

Length of the wire, L

The angle between field and current, Θ

When Θ=90°

The value of the magnetic force is;

F=BIL

When the current is flowing at a 90-degree angle to the magnetic field, the forces acting on a wire carrying a current are the strongest.

Hence, option D is correct.

To learn more about the magnetic field, refer to the link;

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4 0

2 years ago

In a simple RC circuit, at t=0 the switch is closed with the capacitor uncharged. If C=30µF, =50V and R=10k, what is the poten

sergij07 [2.7K]

Answer:

Voltage across the capacitor is 30 V and rate of energy across the capacitor is 0.06 W

Explanation:

As we know that the current in the circuit at given instant of time is

i = 2.0 mA

R = 10 k ohm

now we know by ohm's law

$V = iR$

$V = (2 mA)(10 kohm)$

$V = 20 volts$

so voltage across the capacitor + voltage across resistor = V

$V_c + 20 = 50$

$V_c = 30 V$

Now we know that

$U = \frac{q^2}{2C}$

here rate of change in energy of the capacitor is given as

$\frac{dU}{dt} = \frac{q}{C} \frac{dq}{dt}$

$\frac{dU}{dt} = (30)(2 mA)$

$\frac{dU}{dt} = 0.06 W$

3 0

3 years ago

Hydraulic engineers often use, as a unit of volume of water, the "acre-foot", defined as the volume of water that will cover 1 a

Alex17521 [72]

Answer:

Volume = 1,015 acre-feet (Approx)

Explanation:

Given:

Rain = 1.7 in

Time = 30 min

Area = 29 km²

Find:

Volume in acre-feet

Computation:

1 km = 1,000 m

1 m = 3.28 feet

1 km² = 247.105 acre

d = 1.7 in = 1.7 / 12 = 0.14167 ft

Area = 29 × 247.105 = 7,166.045 acre

Volume = 7,166.045 acre × 0.14167 ft

Volume = 1,015 acre-feet (Approx)

7 0

3 years ago

P*V = n*R*T where P = pressure V = volume n = number of moles R = the universal gas constant T = temperature in degrees Kelvin T

seraphim [82]

The Gay-Lussac's law or Amonton's law states that the pressure of a given amount of a gas is directly propotional to its temperature if its volume is kept constant .

P∝T

and

The Charles Law states that volume of given amount of gas at constant pressure is directly propotional to temperature.

V∝T

So, by Gay-Lussac's law if we increase the temperature the Pressure will increase and by Charles Law, if we increase the temperature the volume will increase.

Therefore, if the temperature of gas increases either the pressure of the gas, the volume of the gas, or both, will increase.

Hence,

Answer is option C

3 0

3 years ago

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