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3 years ago

Define and give 2 examples of kinetic energy. Be sure to include the two factors that make an object’s kinetic energy increase.

1 answer:

8 0

There are radiant and thermal energy
examples of radiant energy are visible light and gamma rays
thermal energy is like a heated swimming pool and a cup of hot tea

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A 4.00-kg mass is attached to a very light ideal spring hanging vertically and hangs at rest in the equilibrium position. The sp

Ahat [919]

Answer:

|v| = 8.7 cm/s

Explanation:

given:

mass m = 4 kg

spring constant k = 1 N/cm = 100 N/m

at time t = 0:

amplitude A = 0.02m

unknown: velocity v at position y = 0.01 m

$y = A cos(\omega t + \phi)\\v = -\omega A sin(\omega t + \phi)\\ \omega = \sqrt{\frac{k}{m}}$

1. Finding Ф from the initial conditions:

$-0.02 = 0.02cos(0 + \phi) => \phi = \pi$

2. Finding time t at position y = 1 cm:

$0.01 =0.02cos(\omega t + \pi)\\ \frac{1}{2}=cos(\omega t + \pi)\\t=(acos(\frac{1}{2})-\pi)\frac{1}{\omega}$

3. Find velocity v at time t from equation 2:

$v =-0.02\sqrt{\frac{k}{m}}sin(acos(\frac{1}{2}))$

5 0

3 years ago

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A 51 kg woman skis down a hill and her kinetic energy is 9.96e4 j. What is her speed?

arlik [135]

Kinetic energy of woman is given as

$KE = 9.96 \times 10^4 J$

mass of woman is given as

$m = 51 kg$

now we will have

$KE = \frac{1}{2}mv^2$

$9.96 \times 10^4 J = \frac{1}{2}(51) v^2$

$v^2 = \frac{9.96 \times 10^4}{25.5}$

$v^2 = 3.91 \times 10^3$

$v = 62.5 m/s$

8 0

4 years ago

A bug flying horizontally at 0.65 m/s collides and sticks to the end of a uniform stick hanging vertically. After the impact, th

irina [24]

The angular momentum is defined as,

$L=I\omega$

Acording to this text we know for conservation of angular momentum that

$L_i=L_f$

Where $L_i$ is initial momentum

$L_f$ is the final momentum

How there is a difference between the stick mass and the bug mass, we define that

Mass of the bug= m

Mass of the stick=10m

At the point 0 we have that,

$L_i=mvl$

Where l is the lenght of the stick which is also the perpendicular distance of the bug's velocity

vector from the point of reference (O), and ve is the velocity

At the end with the collition we have

$L_f=(I_b+I_s)\omega$

Substituting

$L_f=(ml^2+\frac{10ml^2}{3})\omega$

$L_f=\frac{13}{10}ml^2w$

$m(0.65)l=\frac{13}{10}ml^2 \omega$

$\omega=\frac{1}{2l}$

Applying conservative energy equation we have

$\frac{1}{2}(I_b+I_s)\omega^2=mgh+10mgh'$

$\frac{1}{2}(ml^2+\frac{10ml^2}{3})(\frac{1}{2l})^2=mg(l-lcos\theta)+\frac{10}{2}mg(l-lcos\theta)$

Replacing the values and solving

$l=\frac{13}{0.54g}$

Substituting

l=\frac{13}{0.54(9.8)}

$l=2.45cm$

7 0

4 years ago

What is the magnetic field amplitude of an electromagnetic wave whose electric field amplitude is 10v/m?

Nitella [24]

Answer:

$3.33\cdot 10^{-8} T$

Explanation:

For an electromagnetic wave, the relationship between magnetic field amplitude and electric field amplitude is given by

$E=cB$

where

E is the amplitude of the electric field

c is the speed of light

B is the amplitude of the magnetic field

For the electromagnetic wave in this problem, we have

E = 10 V/m is the amplitude of the electric field

So if we solve the formula for B, we find the amplitude of the magnetic field:

$B=\frac{E}{c}=\frac{10 V/m}{3\cdot 10^8 m/s}=3.33\cdot 10^{-8} T$

4 0

3 years ago

Starting at its rightmost position, it takes 2 seconds for the pendulum of a grandfather clock to swing a horizontal distance of

sdas [7]

Answer:

The correct answer is b, x = 9 cos (pi / 2 t)

Explanation:

The equation that describes a simple pendulum is

θ = θ₀ cos (wt + φ)

The angle is measured is radians

θ = x / L

We replace

d / L = x₀ / L cos (wt + φ)

x₀ = 9 in

We replace

d = 9 cos (wt + φ)

Angular velocity is related to frequency and period.

w = 2π f = 2π / T

The period is the time of a complete oscillation T = 4 s

w =2π / 4

w = π / 2

Let's replace

x = 9 cos (π/2 t + φ)

As the system is released from the root x = x₀ for t = 0 s

x₀ = x₀ cos φ

Cos φ = 1

φ = 0°

The final equation is

x = 9 cos (pi / 2 t)

The correct answer is b

8 0

3 years ago

Read 2 more answers