Inertia
<span> An object at rest stays at rest and an object in
motion stays in motion with the same speed and in the same direction
unless acted upon by an unbalanced force.this tendency to retain its motion is referred to as Inertia </span>
Heat<span> capacity ( C ) </span>does change with mass<span>. However, </span>specific heat<span> is the </span>heat<span>capacity per unit </span>mass<span> ( c=Cm ). Therefore if you double the amount of </span>mass<span> in your system, you've doubled its </span>heat<span> capacity, but you've kept the </span>specific heat<span> the same. ... </span>Specific<span> gravity is another such quantity.</span>
Answer:
b. v = 0, a = 9.8 m/s² down.
Explanation:
Hi there!
The acceleration of gravity is always directed to the ground (down) and, near the surface of the earth, has a constant value of 9.8 m/s². Since the answer "b" is the only option with an acceleration of 9.8 m/s² directed downwards, that would solve the exercise. But why is the velocity zero at the highest point?
Let´s take a look at the height function:
h(t) = h0 + v0 · t + 1/2 g · t²
Where
h0 = initial height
v0 = initial velocity
t = time
g = acceleration due to gravity
Notice that the function is a negative parabola if we consider downward as negative (in that case "g" would be negative). Then, the function has a maximum (the highest point) at the vertex of the parabola. At the maximum point, the slope of the tangent line to the function is zero, because the tangent line is horizontal at a maximum point. The slope of the tangent line to the function is the rate of change of height with respect to time, i.e, the velocity. Then, the velocity is zero at the maximum height.
Another way to see it (without calculus):
When the ball is going up, the velocity vector points up and the velocity is positive. After reaching the maximum height, the velocity vector points down and is negative (the ball starts to fall). At the maximum height, the velocity vector changed its direction from positive to negative, then at that point, the velocity vector has to be zero.
Answer:
B. An electric current into a magnetic field
Explanation:
The generation of electrical power requires relative motion between a magnetic field and a conductor. In a generator, mechanical energy is converted into electrical energy. The electricity produced by most generators is in the form of alternating current.
