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jolli1 [7]
3 years ago
10

A horizontal force of 12 Newtons is applied to a 4.0 kg box that slides on a horizontal surface. The box starts from rest moves

a horizontal distance of 10 meters and obtains a velocity of 5.0 m/s. The surface has friction. The friction force is
Group of answer choices

4.9 N.

6.0 N.

7.0 N.

6.5 N.
Physics
1 answer:
Serjik [45]3 years ago
4 0

Answer:

7.0N

Explanation:

F=ma

v2=u2+2as

25=0+20a

a=1.25m/s2

F=ma

F=0.4×1.25

Fn=5N

F=12

12-5=Ff

=7.0N

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What is the frequency of a wave if the speed is 24 m/s and the wave is 2 meters
vekshin1
Velocity=frequency(wavelength)
24m/s=f(2m)
24/2=f(2)/2
12Hz=f
4 0
3 years ago
a solid metal sphere of radius 3.00m carries a total charge of -5.50. what is the magnitude of the electric field at a distance
aivan3 [116]

Answer:

(a) Electric field at 0.250 m is zero.

(b)  Electric field at 2.90 m is zero.

(c) Electric field at 3.10 m is - 5.15 x 10³ V/m.

(d) Electric field at 8.00 m is - 0.77 x 10³ V/m.

Explanation:

Let Q and R are the charge and radius of the solid metal sphere. The solid metal sphere behave as conductor, so total charge Q is on the surface of the sphere.

Electric field inside and outside the metal sphere is :

E = 0 for r ≤ R ( inside )

  = \frac{KQ}{r^{2} } for r > R ( outside )

Here K is electric constant and r is the distance from the center of the metal sphere.

(a) Electric field at 0.250 m is zero as r < R i.e. 0.250 m < 3 m from the above equation.

(b)  Electric field at 2.90 m is zero as r < R i.e. 2.90 m < 3 m from the above equation.

(c) Electric field at 3.10 m is given by the relation as r > R :

E = \frac{KQ}{r^{2} }

Substitute 9 x 10⁹ N m²/C² for K, -5.50 μC for Q and 3.10 m for r in the above equation.

E = - \frac{9\times10^{9}\times5.50\times10^{-6}  }{3.10^{2} }

E = - 5.15 x 10³ V/m

(d) Electric field at 8.00 m is given by the relation as r > R :

E = \frac{KQ}{r^{2} }

Substitute 9 x 10⁹ N m²/C² for K, -5.50 μC for Q and 8.00 m for r in the above equation.

E = - \frac{9\times10^{9}\times5.50\times10^{-6}  }{8^{2} }

E = - 0.77 x 10³ V/m

8 0
3 years ago
Suppose a 4.0-kg projectile is launched vertically with a speed of 8.0 m/s. What is the maximum height the projectile reaches?
eduard

Answer:

h = 3.3 m (Look at the explanation below, please)

Explanation:

This question has to do with kinetic and potential energy. At the beginning (time of launch), there is no potential energy- we assume it starts from the ground. There, is, however, kinetic energy

Kinetic energy = \frac{1}{2}mv^{2}

Plug in the numbers = \frac{1}{2}(4.0)(8^{2})

Solve = 2(64) = 128 J

Now, since we know that the mechanical energy of a system always remains constant in the absence of outside forces (there is no outside force here), we can deduce that the kinetic energy at the bottom is equal to the potential energy at the top. Look at the diagram I have attached.

Potential energy = mgh = (4.0)(9.8)(h) = 39.2(h)

Kinetic energy = Potential Energy

128 J = 39.2h

h = 3.26 m

h= 3.3 m (because of significant figures)

7 0
3 years ago
How does the area of ​​0.3 m2 of iron change when heated from 20 ° C to 60 ° C?
DerKrebs [107]

Answer:

The quantitative relationship between heat transfer and temperature change contains all three factors: Q = mcΔT, where Q is the symbol for heat transfer, m is the mass of the substance, and ΔT is the change in temperature. The symbol c stands for specific heat and depends on the material and phase. The specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC. The specific heat c is a property of the substance; its SI unit is J/(kg ⋅ K) or J/(kg ⋅ ºC). Recall that the temperature change (ΔT) is the same in units of kelvin and degrees Celsius. If heat transfer is measured in kilocalories, then the unit of specific heat is kcal/(kg ⋅ ºC).

Explanation:

6 0
3 years ago
A family took a trip in a car traveling East from Greensboro to Wilmington, NC. Use the Graph to answer the questions below.
kotykmax [81]

Answer:

1). Average speed = 1.5 m per second

2). Average velocity = 1.5 m per second

Explanation:

1). Since, speed is a scalar quantity

   Therefore, average speed of the trip = \frac{\text{Total distance covered}}{\text{Total time taken}}

    From the graph attached,

   Total distance covered = 10 + 10 + 20 + 0 + 20 + 30

                                           = 90 meters

   Total time taken = 60 seconds

    Average speed = \frac{90}{60}

                               = 1.5 meter per second

2). Velocity is a vector quantity.

    Therefore, average velocity = \frac{\triangle d}{\triangle t}

                                                   = \frac{d_{60}-d_0}{60-0}

                                                   = \frac{90-0}{60-0}

                                                   = 1.5 meter per second                        

7 0
3 years ago
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