Answer: The velocity at different marked time points are given as
t1 = -
t2 = +
t3 = +
t4 = -
t5 = 0
Explanation:
The slope of the tangent of the curve indicates the instantaneous velocity. So if the slope of the tangent is positive, that Is, the tangent makes a positive angle (above the horizontal axis) with the horizontal
axis, then the velocity at this point is positive, and if the slope of the tangent is negative, that is the tangent makes a negative angle with the horizontal axis (below the horizontal axis), then the velocity at this point is negative.
When the tangent of the line is parallel to the horizontal axis, the velocity is 0.
From the position-time graph attached, the sign on the instantaneous velocity for each time marked on the graph is given below
t1 = -
t2 = +
t3 = +
t4 = -
t5 = 0
QED!
Hey there!
There's many ways to do it - like melting and evaporating.
For example, we'll use water. Plain old water in a water bottle. Right now, it's in its liquid state of matter, but say you put it in the freezer for an hour. That would change its state of matter to solid, since it would be solid ice. Now, if you were to put it out in the sun on a blazing hot day for a couple of hours, it would evaporate and become water vapor, a gas. Lastly, if you can cool that water vapor it becomes a liquid again.
Hope this helps!
Consider the upward direction of motion as positive and downward direction of motion as negative.
a = acceleration due to gravity in downward direction = - 9.8 
v₀ = initial velocity of rock in upward direction = ?
v = final velocity of rock at the highest point = 0 
t = time to reach the maximum height = 4.2 sec
Using the kinematics equation
v = v₀ + a t
inserting the values
0 = v₀ + (- 9.8) (4.2)
v₀ = 41.2
It would be option C. It rotates, or spins, on its axis, but it revolves around the sun.
