Answer:
Vi = 32 [m/s]
Explanation:
In order to solve this problem we must use the following the two following kinematics equations.
The negative sign of the second term of the equation means that the velocity decreases, as indicated in the problem.
where:
Vf = final velocity = 8[m/s]
Vi = initial velocity [m/s]
a = acceleration = [m/s^2]
t = time = 5 [s]
Now replacing:
8 = Vi - 5*a
Vi = (8 + 5*a)
As we can see we have two unknowns the initial velocity and the acceleration, so we must use a second kinematics equation.
where:
d = distance = 100[m]
(8^2) = (8 + 5*a)^2 - (2*a*100)
64 = (64 + 80*a + 25*a^2) - 200*a
0 = 80*a - 200*a + 25*a^2
0 = - 120*a + 25*a^2
0 = 25*a(a - 4.8)
therefore:
a = 0 or a = 4.8 [m/s^2]
We choose the value of 4.8 as the acceleration value, since the zero value would not apply.
Returning to the first equation:
8 = Vi - (4.8*5)
Vi = 32 [m/s]
Answer:
Velocity
Explanation:
"The principle is that the slope of the line on a position-time graph is equal to the velocity of the object. If the object is moving with a velocity of +4 m/s, then the slope of the line will be +4 m/s."
^^This explanation is from physicsclassroom.com
<h2>
Answer: 540 J</h2>
Explanation:
The Work 
done by a Force 
refers to the release of potential energy from a body that is moved by the application of that force to overcome a resistance along a path.
Now, when the applied force is constant and the direction of the force and the direction of the movement are parallel, the equation to calculate it is:
(1)
In this case both (the force and the distance in the path) are parallel (this means they are in the same direction), so the work performed is the product of the force exerted to push the box 
by the distance traveled 
.
Hence:
(2)
Answer:
1:4
Explanation:
The formula for calculating kinetic energy is:
If the mass is multiplied by 4, then, the kinetic energy must be increased by 4 as well. Since they will be travelling at the same speed when they are at the same point, the relation between KA and KB must be 1:4 or 1/4. Hope this helps!
Answer:
Two times as much
Explanation:
The equation for gravitational force is: Fg = GMm/r^2 with G being the universal gravitational constant.
So to make things easier we'll set r equal to 1 since it's a constant as well as G.
Then we're left with Fg=Mm with M being the mass of the sun and m being the mass of the earth.
So if m is constant and supposedly equals 1 then Fg=M so Fg is proportional to M therefore if M doubles then Fg doubles.
