Answer:
A velocity time graph shows the change of velocity of an object with respect ot time. If the slope of the graph is increasing in the postive region, it means that the velocity is changing, if the slope is decreasing, it means the the velocity is decreasing, but the object is moving in the same direction (positve direction).
If this slope intersects the graph at x-axis, it means that the body has 0 velocity and has become still. After that, if the line enters in the negative region, it means that its velocity is started to increases again, but the body is movinging in the opposite direction (negative direction)
A speed does not involve the element of direction.
Electric field lines always begin at positive charges (or at infinity) and end at negative charges (or at infinity).
One could also say that the lines we use to represent an electric field indicate the direction in which a positive test charge would initially move when released from rest.
What about cod my guy which one are we talking ?
An estimated value for gravity at a distance r from the middle of the Earth can be gotten by supposing that the Earth's density is spherically symmetric. The gravity hinge on only on the mass inside the sphere of radius r. All the assistances from outside cancel out as a fall out of the inverse-square law of gravitation. Another result is that the gravity is the same as if all the mass were concentrated at the midpoint. Therefore, the gravitational acceleration at this radius is
g(r) = GM(r) / r²
M(r) = mass enclosed by radius r.
If the Earth had a continual density ρ, the mass would be M(r) = (4/3)πρr³ and the dependence of gravity on distance would be
g(r) = (4/3)πGρr
G = 6.674e-11 m³/kgs²
