Answer:
d. Potential energy is converted to kinetic energy; the kinetic energy is then converted into the work of bringing the body to a stop
Explanation:
- When the person starts his/her fall from a certain height h, he/she possesses gravitational potential energy:
where m is the mass of the person, g is the acceleration due to gravity, h is the height.
- During the fall, the height h decreases, while the speed of the person increases, so gravitational potential energy is converted into kinetic energy:
where
m is the mass of the person
v is the speed
- Just a moment before hitting the ground, h=0, so all the potential energy has been converted into kinetic energy
- When the person hits the ground, he/she comes a stop: this means that now the speed is zero (v=0), so the kinetic energy is zero as well. This occurs because all the kinetic energy has been converted into the work of bringing the body to a stop. (the work has been done by the ground on the person)
Answer:
17.64 km/h
Explanation:
mass of car, m = 1000 kg
Kinetic energy of car, K = 1.2 x 10^4 J
Let the speed of car is v.
Use the formula for kinetic energy.
By substituting the values
v = 4.9 m/s
Now convert metre per second into km / h
We know that
1 km = 1000 m
1 h = 3600 second
So,
v = 17.64 km/h
Thus, the reading of speedometer is 17.64 km/h.
Answer:
The answers are located in each of the explanations showed below
Explanation:
a)
(i) Surface Tension: The tensile force that causes this tension acts parallel to the surface and is due to the forces of attraction between the molecules of the liquid. The magnitude of this force per unit of length is called surface tension.
σ = F/l [N/m]
where:
F = force [N]
l = length [m]
σ = Surface Tension [N/m]
(ii) Frequency is the number of repetitions per unit of time of any periodic event.
f = 1/T [1/s] or [s^-1] or [Hz]
where:
T = period [s] or [seconds]
f = frecuency [Hz] or [hertz]
(iii) Each of the units will be shown for each variable
v = velocity [m/s]
a = accelertion [m/s^2]
s = displacement [m]
b) To find the velocity we must derivate the function X with respect to t because this derivate will give us the equation for the velocity, it means:
ii) replacing in the derivated equation.
iii) the average velocity is defined by the expresion v = x/t
2
a) Pascal's principle or Pascal's law, where the pressure exerted on an incompressible fluid and in balance within a container of indeformable walls is transmitted with equal intensity in all directions and at all points of the fluid.
Therefore:
P1 = pressure at point 1.
P2 = pressure at point 2.
P1 = F1/A1
P2= F2/A2
b) One of the applications of the surface tension is the <u>capillarity</u> this is a property of liquids that depends on their surface tension (which, in turn, depends on the cohesion or intermolecular force of the liquid), which gives them the ability to climb or descend through a capillary tube.
Other examples of surface tension:
The mosquitoes that can sit on the water.
A clip on the water.
Some leaves that remain floating on the surface.
Some soaps and detergents on the water.
a)
b) 1.96 N
c) 1.96 N
Explanation:
a)
To find the box's acceleration, we have to find first the net force acting on the box in the horizontal direction.
We have:
- The forward force of 3.55 N
- The backward, resistive force of 0.52 N
So, the net force forward is
Now we can find the acceleration by using Newton's second law of motion, which states that:
where
m = 0.200 kg is the mass of the box
a is its acceleration
And solving for a, we find the acceleration:
b)
The gravitational force on an object is the force with which the object is pulled towards the ground by the Earth.
It is given by
where
m is the mass of the object
g is the gravitational field strength
In this problem we have
m = 0.200 kg is the mass of the box
is the gravitational field strength
So, the gravitational force on the box is
c)
The normal force is the reaction force exerted by the floor on the box, in the upward direction.
In order to find the magnitude of this force, we apply Newton's second law of motion along the vertical direction.
We have two forces in this direction:
- The gravitational force, W, downward
- The normal force, N, upward
So the net force is
According to Newton's second law,
However, the box is at rest in the vertical direction, so the vertical acceleration is zero:
This means that the net force is zero:
And so, we can find the normal force: