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2 years ago

A fast-moving car has 0.5 MJ of kinetic energy.

Physics

1 answer:

DerKrebs [107]2 years ago

6 0

Answer:

-0.5 MW

Explanation:

For this we can use the principle of work and energy, which states that:

T₁ + ∑U₁₋₂ = T₂

Where T is kinetic energy (in situations one and two) and U is the sum of all work done (between situations one and two).

So, since the car is first moving with a kinetic energy of 0.5 MJ:

T₁ = 0.5 MJ = 0.5 · 10⁶ J

On top of this, we know that the car comes to a halt, using this as situation 2:

T₂ = 0 J

Filling in the equation:

⇒ 0.5 · 10⁶ + U = 0

⇒ U = -0.5· 10⁶ [W] (unit of work is watts)

= -0.5 MW

Thinking about the sign convention, we see that the brake force will point to the back of the car (backward), and the distance the car will travel before stopping will be forward, oposite directions and thus negative work.

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Consider a 100 g object dropped from a height of 1 m. Assuming no air friction (drag), when will the object hit the ground and a

Katyanochek1 [597]

Answer:

speed and time are Vf = 4.43 m/s and t = 0.45 s

Explanation:

This is a problem of free fall, we have the equations of kinematics

Vf² = Vo² + 2g x

As the object is released the initial velocity is zero, let's look at the final velocity with the equation

Vf = √( 2 g X)

Vf = √(2 9.8 1)

Vf = 4.43 m/s

This is the speed with which it reaches the ground

Having the final speed we can find the time

Vf = Vo + g t

t = Vf / g

t = 4.43 / 9.8

t = 0.45 s

This is the time of fall of the body to touch the ground

3 0

3 years ago

A pendulum is made up of a small sphere of mass 0.500 kg attached to a string of length 0.950 m. The sphere is swinging back and

Semenov [28]

Answer:

W = 0.842 J

Explanation:

To solve this exercise we can use the relationship between work and kinetic energy

W = ΔK

In this case the kinetic energy at point A is zero since the system is stopped

W = K_f (1)

now let's use conservation of energy

starting point. Highest point A

Em₀ = U = m g h

Final point. Lowest point B

Em_f = K = ½ m v²

energy is conserved

Em₀ = Em_f

mg h = K

to find the height let's use trigonometry

at point A

cos 35 = x / L

x = L cos 35

so at the height is

h = L - L cos 35

h = L (1-cos 35)

we substitute

K = m g L (1 -cos 35)

we substitute in equation 1

W = m g L (1 -cos 35)

let's calculate

W = 0.500 9.8 0.950 (1 - cos 35)

W = 0.842 J

7 0

3 years ago

Calculate the angle of refraction of 30.0° light shines from water into ice. The indices of refraction for water and ice are 1.3

WITCHER [35]

Answer:

The angle of refraction Ø2 equals 62.95° ≈ 63°

Explanation:

The relationship between the angles of incidence and

refraction , with respect to light or other waves passing through two different substances or media, such as glass, water or air is given by Snell's Law.

Snell's Law states that the when light travels from one medium to another, it generally refracts.

It is given by the mathematical expression;

[SinØ1°/SinØ2°] = [n2/n1]

Cross multiplying, we have;

n1 × SinØ1° = n2 × SinØ2°

where, n is the indices of refraction of each substance

Ø is the angle between the ray and the line normal to the surface.

Given the following values;

n1 = 1.36 n2 = 1.31 Ø1 = 30° Ø = ?

n1 × SinØ1° = n1 × SinØ2°

SinØ2° = [n1 × SinØ1°]/n2

substituting the values respectively;

SinØ2° = [1.36 × Sin30°]/1.31

SinØ2° = [1.36 × 0.5]/1.31

SinØ2° = 0.68 × 1.31

SinØ2° = 0.8906

Ø2° = Sin–¹(0.8906)

Ø2° = 62.95° ≈ 63°

4 0

3 years ago

Which picture represents 2NO2?

wariber [46]

2NO2 means that there is 2 oxygen atoms and one nitrogen with two sets of that. So its the third one

3 0

3 years ago

Read 2 more answers

What are examples of non mechanical energy

ExtremeBDS [4]

Atoms, molecules, electrons, photons, protons etc.

3 0

3 years ago