A car is moving from rest and the velocity increases to 30 m/s in 4 seconds. Calculate its acceleration.

In a simple model of the hydrogen atom, the electron moves in a circular orbit of radius 0.053nm around a stationary proton. par

Alenkasestr [34]

Here the force that is applied between the electron and proton is centripetal, so equate the two forces to determine the velocity.
We know charge of the electron which for both Q1 and Q2, e = 1.60 x 10^-19 C
The Coulombs Constant k = 9.0 x 10^9
Radius r = 0.053 x 10^-9m = 5.3 x 10^-11 m
Mass of the Electron = 9.11 x 10^-31
F = k x Q1 x Q2 / r^2 = m x v^2 / r(centripetal force)
ke^2 / r^2 = m x v^2 / r => v^2 = ke^2 / m x r
v^2 = ((1.60 x 10^-19)^2 x 9.0 x 10^9) / (9.11 x 10^-31 x 5.3 x 10^-11 )
v^2 = 4.77 x 10^12 = 2.18 x 10^6 m/s
Since one orbit is the distance,
one orbit = circumference = 2 x pi x r; distance s = v x t.
v x t = 2 x pi x r => t = (2 x 3.14 x 5.3 x 10^-11) / (2.18 x 10^6)
t = 33.3 x 10^-11 / 2.18 x 10^6 = 15.27 x 10^-17 s
Revolutions per sec = 1 / t = 1 / 15.27 x 10^-17 = 6.54 x 10^15 Hz

6 0

3 years ago

9. Luke is an astronaut that moves his position in the space shuttle by climbing a

BartSMP [9]

Explanation:

Remember that power is defined as how much Work is done per unit of time.

$P = \frac{dW}{dt}$

Work is defined as the amount of force applied across a certain distance.

$W = F*d$

Since in both cases of climbing the ladder (on Earth and the moon), Luke coveres the same amount of distance in the same amount of time, we are only left with one difference between the two cases - gravity.

If you were to carry your backpack on the moon with the same load of text books, it would take less force to pick it up on the moon. Therefore, Luke expends less effort on the environment with less gravity - the moon.

To find the difference factor - you would want to divid the gravitational contants between earth and the moon.

6 0

3 years ago

Read 2 more answers

4. Johnny exerts a 3.55 N rightward force on a 0.200-kg box to accelerate it across a low-friction track. If the total resistanc

muminat

a) $15.2 m/s^2$

b) 1.96 N

c) 1.96 N

Explanation:

a)

To find the acceleration of the box, we apply Newton's second law of motion:

$\sum F=ma$

where

$\sum F$ is the net force on the box

m is the mass of the box

a is its acceleration

Here we have to consider the horizontal direction, which is the one in which the box is moving. The net force is given by:

$\sum F=3.55 N - 0.52 N=3.03 N$

which is the difference between the forward force and the resistive force. Then we have

m = 0.200 kg (mass of the box)

Therefore, the acceleration of the box is:

$a=\frac{\sum F}{m}=\frac{3.03}{0.200}=15.2 m/s^2$

b)

The gravitational force (also called weight) is the force with which an object is pulled by the Earth towards the Earth's centre.

It is given by

$F_g = mg$

where

m is the mass of the object

g is the acceleration due to gravity

In this problem, we have:

m = 0.200 kg is the mass of the box

$g=9.8 m/s^2$ is the acceleration due to gravity

Therefore, the gravitational force on the box is:

$F_g=(0.200)(9.8)=1.96 N$

c)

The normal force is the force with which a surface pushes back on an object.

For an object lying on a flat surface, there are two forces acting along the vertical direction:

- The gravitational force, $F_g$ , which pushes the object downward

- The normal force, N, which pushes the object upward

As the object is at rest, the vertical acceleration of the object is zero, therefore according to Newton's second law of motion, the net force must be zero:

$\sum F=F_g-N=0$

Which means that the normal force is equal to the gravitational force:

$N=F_g$

And so, for the box in this problem, the normal force is

$N=1.96 N$

6 0

4 years ago

Which example(s) below involve zero physics work? check all that apply. check all that apply. a rope supports a swinging chandel

Westkost [7]

In physics, work is defined to be the product of force and distance. So to have work, there must be some movement and the force must be parallel to the direction of the movement. In this case, work is zero when there is no movement and the force is not parallel to the movement. Hence, the answers are:

a rope supports a swinging chandelier

a person pushes a car stuck in the snow but the car does not move

a person holds a child

7 0

3 years ago

A linear accelerator uses alternating electric fields to accelerate electrons to close to the speed of light. A small number of

kobusy [5.1K]

Answer:

8.1 x 10^13 electrons passed through the accelerator over 1.8 hours.

Explanation:

The total charge accumulated in 1.8 hours will be:

Total Charge = I x t = (-2.0 nC/s)(1.8 hrs)(3600 s/ 1 hr)

Total Charge = - 12960 nC = - 12.96 x 10^(-6) C

Since, the charge on one electron is e = - 1.6 x 10^(-19) C

Therefore, no. of electrons will be:

No. of electrons = Total Charge/Charge on one electron

No. of electrons = [- 12.96 x 10^(-6) C]/[- 1.6 x 10^(-19) C]

No. of electrons = 8.1 x 10^13 electrons

6 0

3 years ago