If you lift a five pound object 18 inches how many joules of energy did yo use?

Describe an example of Newton's 3rd Law of Motion (for every action there is an equal and opposite reaction).

Alina [70]

The motion of an airplane when the pilot changes the throttle setting of the engine is described by the first law. The motion of a ball falling down through the atmosphere, or a model rocket being launched up into the atmosphere are both examples of Newton's first law.

8 0

2 years ago

A 0.100-kg ball traveling horizontally on a frictionless surface approaches a very massive stone at 20.0 m/s perpendicular to wa

Gennadij [26K]

Answer:

Change in momentum of the stone is 3.673 kg.m/s.

Explanation:

Given:

Mass of the ball on the horizontal the surface, m = 0.10 kg

Velocity of the ball with which it hits the stone, v = 20 m/s

According to the question it rebounds with 70% of the initial kinetic energy.

We have to find the change in momentum i.e Δp

Before that:

We have to calculate the rebound velocity with which the object rebounds.

Lets say that the rebound velocity be "v1" and KE remaining after the object rebounds be "KE1".

⇒ $KE_1=0.7\times \frac{mv^2}{2}$

⇒ $KE_1=0.7\times \frac{0.10\times (20)^2}{2}$

⇒ $KE_1=0.7\times \frac{0.10\times 400}{2}$

⇒ $KE_1=14$ Joules (J).

Rebound velocity "v1".

⇒ $KE_1=\frac{m(v_1)^2}{2}$

⇒ $v_1 = \sqrt{\frac{2KE_1}{m} }$

⇒ $v_1 = \sqrt{\frac{2\times 14}{0.10} }$

⇒ $v_1=16.73$

⇒ $v_1=-16.73$ m/s ...as it rebounds.

Change in momentum Δp.

⇒ $\triangle p= m\triangle v$

⇒ $\triangle p= 0.10\times (20-(-16.73)$

⇒ $\triangle p= 0.10\times (20+16.73)$

⇒ $\triangle p= 0.10\times (36.73)$

⇒ $\triangle p = 3.673$ Kg.m/s

The magnitude of the change in momentum of the stone is 3.673 kg.m/s.

5 0

3 years ago

According to the theory of plate tectonics, what drives the motion of the continents?

Alex

I’m deciding between E or D.. because for E it’s saying it’s changing ocean currents, but I’m thinking does that mean the earths precipitation or their climate. Best go with E, hope this helps

7 0

3 years ago

Read 2 more answers

It took 500 N of force to push a car 4 meters. How much work was done?

djverab [1.8K]

Answer:

200 J

Explanation:

W = F S

W= 500 x 4

W = 2000

6 0

2 years ago

Use Newton's laws to explain why a falling object dropped from a 57m tower accelerates initially but then reaches constant veloc

snow_lady [41]

Answer:

At the point of dropping the object, by Newton's first law due to gravitational force $F_g$ = m × g, accelerates

By Newton's Second law the object reaches impacts on the air with the gravitational force resulting in changing momentum of m×(Final Velocity - Initial Velocity)

As the velocity increases, the rate of change of momentum becomes equivalent to the gravitational force and by Newton's third law, the action action and reaction are equal and opposite hence they cancel each other out

The body then moves at a constant uniform motion down according to Newton's first law

Explanation:

At the point the object of mass, m, is dropped from the height of the tower, the only force acting on the object is the gravitational force such that the object has an acceleration which is the acceleration due to gravity, g, and the gravitational force is therefore = m × g

As the speed of the object increases while the object is falling with the gravitational acceleration the rate at which the object cuts through layers of air which (by Newton's first law of motion, are at rest ) has some buoyancy effect also increases therefore, the object is constantly increasingly changing the momentum of the air which by Newton's second law results, at an high enough velocity, and by Newton's third law, in a force equal to the applied gravitational force

Therefore, the force of the air drag becomes equal to the gravitational force, cancelling each other out and the object then moves according to Newton;s first law, in uniform motion of a constant speed while still falling down.

5 0

2 years ago