Physics, 21.02.2020 06:51 nyceastcoast

Can y’all help with number 2, 4,5,6?

Answers: 2

Show answers

Answers

Answer from: rebekahlm

2)Ek = 686.7[J]; 4) see the explanation part; 5) B) Remained motionless; 6) P = 339 [watt]

Explanation:

Using, the principle of energy conservation we can find the kinetic energy of the rock. We must bear in mind that the potential energy as the rock falls is becoming kinetic energy.

$E_{p}=E_{k}\\E_{p}=m*g*h\\where:\\m = mass = 1[kg]\\g=gravity=9.81[m/s^2]\\h=elevation[m]\\$

Now replacing the values:

$E_{p}=1*9.81*(90-20)\\E_{p}=686.7[J]\\Therefore\\E_{k}=686.7[J]$

False, the work is always done in the same direction as the application of force.True, energy is always conserved and transformed from one form to another, that is why the sum of potential and kinetic energies will remain constant.False, the moment is defined as the change of speed in a body, under the effect of force in a time interval.False, the kinetic energy is increasing, while the potential energy is decreasing

B) Remained motionless

The reason is that work is defined as the product of force by distance, when there is no work for this case, it is because there is no movement of the object due to force.

We recall that work is defined as the product of force by distance

W = F * d

W = 113 * 27

W = 3051[J]

And power is defined as the amount of work performed over a time interval.

Power = W/t

Power = 3051/9

Power = 339 [watt]

Answer from: Quest

No it doesnt because it can be any number.

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

Another question on Physics

Physics, 21.06.2019 15:30

What defines the mass number of an isotope? a. the sum of the neutrons and protons b. the sum of the neutrons and electrons c. the number of neutrons d. the number of protons

Answers: 1

Answer

Physics, 22.06.2019 05:30

Could someone me find the answer to this problem.

Answers: 1

Answer

Physics, 22.06.2019 08:30

A17,250 kg rocket is pushed with a thrust of 6,450,284 n. what is the acceleration of the rocket?

Answers: 1

Answer

Physics, 22.06.2019 10:20

Asmall object with mass 0.200 kg swings back and forth on the lower end of a light rope that is 3.00 m long. the upper end of the rope is attached to the ceiling. as the object swings through its lowest position, where the rope is vertical, the speed of the object is 5.80 m/s. at this point in the motion, what is the tension in the rope? (use g = 9.80 m/s2.)