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2 years ago

8

Alice kicks a soccer ball with a mass of 2 kg. The ball leaves the ground moving 30 meters per second. What is the kinetic energ

y of the soccer ball? (KE = 1/2mv2)I

1 answer:

sleet_krkn [62]2 years ago

5 0

By using the formula:

• K.E = ½mv²

mass, m = 2 kg
Velocity, v = 30 m/s

→ K.E = ½ × 2 × (30)² J

→ K.E = (30)² J

→ K.E = 900 J (Answer)

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3 years ago

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Your local AM radio station broadcasts at a frequency of f = 1100 kHz. The electric-field component of the signal you receive at

Lina20 [59]

Answer:

(a) 272.73 m

(b) 0.338 N/C

Explanation:

frequency, f = 1100 kHz = 1100 x 1000 Hz

E(t) = Eo Sin(2πft)

Eo = 0.62 N/C

(a) Velocity of light, c = 3 x 10^8 m/s

wavelength, λ = c / f = (3 x 10^8) / (1100000) = 272.73 m

Thus, the wavelength is 272.73 m.

(b) at t = 3.1 microsecond = 3.1 x 10^-6 s

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3 years ago

A 51.0 kg cheetah accelerates from rest to its top speed of 31.7 m/s. HINT (a) How much net work (in J) is required for the chee

andrey2020 [161]

(a) $2.56\cdot 10^4 J$

The work-energy theorem states that the work done on the cheetah is equal to its change in kinetic energy:

$W= \Delta K = \frac{1}{2}mv^2 - \frac{1}{2}mu^2$

where

m = 51.0 kg is the mass of the cheetah

u = 0 is the initial speed of the cheetah (zero because it starts from rest)

u = 31.7 m/s is the final speed

Substituting, we find

$W=\frac{1}{2}(51.0 kg)(31.7 m/s)^2 - \frac{1}{2}(51.0 kg)(0)^2=2.56\cdot 10^4 J$

(b) 6.1 cal

The conversion between calories and Joules is

1 cal = 4186 J

Here the energy the cheetah needs is

$E=2.56\cdot 10^4 J$

Therefore we can set up a simple proportion

$1 cal : 4186 J = x : 2.56\cdot 10^4 J$

to find the equivalent energy in calories:

$x=\frac{(1 cal)(2.56\cdot 10^4 J)}{4186 J}=6.1 cal$

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3 years ago

Two long, parallel wires are separated by a distance of 2.00 cm . The force per unit length that each wire exerts on the other i

RUDIKE [14]

Answer:

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Explanation:

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b) knowing that for a two parallel conductor carrying current in the same direction attracts each other, and for a two parallel conductors carrying carying current in opposite direction repels eachother.

therefore, since the two wire repel each other then the current in the second wire must flow in the opposite direction of the current in the first wire.

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kodGreya [7K]

IF there is no air resistance, then he could drop a feather, a piece
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4 years ago

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