What’s an example of contact friction

7. Which best describes the energy change th pushes a large rock down a hill?

svlad2 [7]

Answer:

B

Explanation:

Gravitational Energy is the energy of position or place. A rock resting at the top of a hill contains gravitational Potential energy. Hydropower, such as water in a reservoir behind a dam, is an example of gravitational potential energy.

6 0

3 years ago

Read 2 more answers

a large truck has a mass of 20000kg. it is traveling at 28m/s along a staright road . calculate the kinetic energy

Semmy [17]

Answer:

The answer is

Explanation:

The kinetic energy KE of an object given it's mass and velocity can be found by using the formula

$KE = \frac{1}{2} m {v}^{2} \\$

where

m is the mass

v is the velocity

From the question

m = 20000kg

v = 28 m/s

It's kinetic energy is

$KE = \frac{1}{2} \times 20000 \times {28}^{2} \\ = 10000 \times 784$

We have the final answer as

Hope this helps you

3 0

3 years ago

Rectangular plate has a voltage of +180V and plate to the first plate) has a 'voltage of -5V. Determie another rectangular plate

3241004551 [841]

For a Rectangular plate has a voltage of +180V and a 'voltage of -5V. , the second plate has the Electric field mathematically given as

E=21.5*10^3v/m

<h3>What is the field strength?</h3>

Generally, the equation for the Electric field is mathematically given as

E=v/d

Where

v={180-(-5)}v

v=185v

Therefore

E=185/8.6*10^{-3}

E=21.5*10^3v/m

In conclusion, Electric field

E=21.5*10^3v/m

Read more about electric field

brainly.com/question/9383604

4 0

2 years ago

The tub of a washer goes into its spin-dry cycle, starting from rest and reaching an angular speed of 5.0 rev/s in 8.0 s. At thi

alisha [4.7K]

Answer:

The total number of revolution is 50 rev.

Explanation:

Given that,

Angular speed = 5.0 rev/s

Time = 8.0 s

We need to calculate the angular acceleration

Using equation of angular motion

$\omega_{f}-\omega_{i}=\alpha t$

Put the value into the formula

$5.0-0=\alpha\times8.0$

$\alpha=\dfrac{5.0}{8.0}$

$\alpha=0.625\ rev/s^2$

We need to calculate the angular displacement

Using equation of angular motion

$\theta=\omega_{i}t+\dfrac{1}{2}\alpha t^2$

Put the value into the formula

$\theta=0+\dfrac{1}{2}\times0.625\times(8.0)^2$

$\theta=20\ rev$

Now, The washer coming to rest from top spin

We need to calculate the angular acceleration

Using equation of angular motion

$\omega_{f}-\omega_{i}=\alpha t$

$\alpha=\dfrac{\omega_{f}-\omega_{i}}{t}$

$\alpha=\dfrac{0-5}{12}$

$\alpha=−0.4167\ rev/s^2$

We need to calculate the angular displacement

Using formula of displacement

$\theta'=\omega_{i}t+\dfrac{1}{2}\alpha t^2$

Put the value into the formula

$\theta'=5\times12+\dfrac{1}{2}\times(-0.4167)\times12^2$

$\theta'=30\ rev$

We need to calculate the total number of revolution

$\theta''=\theta+\theta'$

$\theta''=20+30$

$\theta''=50\ rev$

Hence, The total number of revolution is 50 rev.

5 0

4 years ago

The radius of a conducting wire is doubled .What will be the ratio of its new specific resistance to the old one?

sladkih [1.3K]

The equation for the resistance R is: R=ρ*(l/A), where, ρ is electrical resistivity, l is the length of the conductor, and A is the surface area.

The initial surface area is:

A=r²π, then when we double the radius we get:

A₁=(2*r)²π=4*r²π=4*A

Initial resistance is: R=ρ*(l/A).

When we double the radius, resistance is: R₁=ρ*{ l / (4*A) }

The ratio of the new resistance to the old one:

R₁/R=[ρ*(l/A)] / [ ρ* { l / (4*A) } ] = ρ, l and A cancel out and we get:

R₁/R=(1/1)/(1/4)=4/1

7 0

4 years ago