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Eduardwww [97]
2 years ago
10

A 2-kg box is pushed to the right by a force of 4 N for a distance of 32 m. It has an initial velocity of 4 m/s to the right. NO

TE: Since this problem gives the DISTANCE ∆x traveled, FIRST look at kinetic energy and calculate the NET WORK using Wnet = F ∆x = ∆K. After the kinetic energy values are calculated, then calculate the momenta and impulse values. Remember that on quiz and test problems, you will need to decide which values should be calculated first.
a) What is the initial momentum pi of the box?

8 kg m/s

You are correct. Computer's answer now shown above.

Your receipt no. is 160-3868 Help: Receipt Previous Tries

b) What is the impulse or change in momentum ∆p of the box?

_____kg m/s

Tries 0/2

c) What is the final momentum pf of the box?

_____kg m/s

Tries 0/2

d) What is the initial kinetic energy Ki of the box?

_____J

Tries 0/2

e) What is the change in kinetic energy ∆K of the box?

_____J

Tries 0/2

f) What is the final kinetic energy Kf of the box?

_____J

Tries 0/2

g) How long ∆t does it take for the box to travel the distance of 32 m?

_____s

Tries 0/2
Physics
1 answer:
rewona [7]2 years ago
6 0

Answer: a) 8 Kg m/s b) 16 Kg m/s c) 24 Kg m/s d) 16 J e) 128 J f) 144 J

              g) 4 s

Explanation:

a) As momentum by definition is the product of mass times the velocity (is a vector quantity), we can write in this case the following:

pi = m. v₀ = 2 Kg . 4 m/s = 8 Kg. m/s

b) In order to get the change in momentum, we need to get first the final speed of the object.

As we have the total distance travelled, and we could find the acceleration, we could use a kinematic equation to solve the question, but later we will need the kinetic energy, it would be better to apply the work-energy theorem, and calculate ΔK as the work done by external force F, as follows:

ΔK = F . d = 1/2 m (vf² - v₀²)

As we know F, d, m, and v₀, we can solve the equation above for vf:

vf = 12 m/s

So, we can compute the final momentum as follows:

pf = m. vf = 2 Kg. 12 m/s = 24 Kg. m/s

Finally, we can find the change in momentum, as the difference between the final momentum and the initial one, calculated in a):

Δp = pf - pi = 24 Kg. m/s - 8 Kg. m/s = 16 Kg. m/s

c) As we have already found, final momentum is as follows:

pf = m . vf = 2 Kg. 12 m/s = 24 Kg. m/s

d) By definition the initial kinetic energy of the box is as follows:

Ki = 1/2 m v₀² = 1/2. 2 Kg .4² m²/s² = 16 J

e) We can find the change in the kinetic energy taking directly the difference between the final and initial ones, as follows:

ΔK = Kf - Ki = 1/2. 2 Kg (12² - 4²) m²/s² = 128 J

f) From above, we have Kf = 1/2 m. vf² = 1/2 . 2 Kg. 12² m²/s² = 144 J

g) As we know the magnitude of F, and the value of m, we can find the acceleration (assumed constant) , applying Newton's Second Law, as follows:

Fext = m .a ⇒ a = F/m = 4 N / 2 Kg = 2 m/s²

Appying the definition of acceleration, we can solve for t, as follows:

t = (vf-v₀) / a = (12 m/s - 4 m/s) / 2 m/s² = 4 s

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If the only force exerted on a star far from the center of the Galaxy (r = 7.40 ✕ 1020 m) is the gravitational force exerted by
lina2011 [118]

Answer:

The value is  v = 1.309*10^{5}\ m/s

Explanation:

The radius is r = 7.40 *10^{20} \  m

The mass of the ordinary matter is M_{rod} =  1.90 *10^{41}\  kg

Generally the speed of the star is mathematically represented as

         v = \sqrt{\frac{G * M}{r} }

Here G is the gravitational constant with a value

        G = 6.67384 * 10^{-11}

So

      v = \sqrt{\frac{6.67384 * 10^{-11} * 1.90 *10^{41}}{7.40 *10^{20}} }

=>    v = 1.309*10^{5}\ m/s

8 0
2 years ago
A 10v battery is connected in series with 2 resistors. R1 is 1 ohm and R2 is 4 ohms. What is the current that goes across R1?
Digiron [165]

Answer:

Current in circuit = 2 amp

Explanation:

Given:

Voltage of battery = 10 V

First Resistance R1 = 1 ohm

Second Resistance R2 = 4 ohm

Resistor connected in series

Find:

Current in circuit

Computation;

Resistor connected in series

So,

Total resistance R = First Resistance R1 + Second Resistance R2

Total resistance R = 1 ohm + 4 ohm

Total resistance R = 5 ohm

Current in circuit = V / R

Current in circuit = 10 / 5

Current in circuit = 2 amp

7 0
2 years ago
A ball is dropped from a height of 20 meters. At what helght does the ball have a velocity of 10 meters/second?
Sunny_sXe [5.5K]

Answer:

5.10 meters.

Explanation:

v²=u²+2gh

or, (10)²=(0)²+2×9.8×h

or, 19.6h=100

or, h=5.10 meters

Hope, this helps you.

8 0
2 years ago
1 point
Trava [24]

Answer:

Their number should increase

Explanation:

The photoelectric effect is a phenomenon that causes the ejection of electrons from that metal as light shined onto a metal surface. Only certain frequencies of light can cause the ejection of electrons. However, if the frequency of the incident light is too low then no electrons were ejected even if the intensity of the light was very high. If the frequency of the light was higher then electrons were able to be ejected from the metal surface even if the intensity of the light was very low.

According to the accepted wave theory, light of any frequency will cause electrons to be emitted. Kinetic energy emitted by the electrons depends upon the intensity of light.

According to the accepted wave theory, number of electrons being ejected by the metal should increase

5 0
2 years ago
A wire is oriented along the x-axis. It is connected to two batteries, and a conventional current of 2.6 A runs through the wire
lana66690 [7]

Answer:

the magnitude of the magnetic force on the wire is 0.2298 N

Explanation:

Given the data in the question;

we know that, the magnitude of magnetic force is given as;

|F_{mg}^> | = I(B^> × L^> )

given that

I = 2.6 A

B^> = 0.17

L^> = 0.52

so we substitute

|F_{mg}^> | = 2.6( 0.17i" × 0.52j" )

|F_{mg}^> | = 0.2298 N

Therefore, the magnitude of the magnetic force on the wire is 0.2298 N

4 0
3 years ago
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