Answer:
D. Closed Surfaces
The gaussian surface could be a sphere and can be applied to flat surfaces, but it's always a closed surface.
Reduce speed or slow down.
Orange signs and cones are usually present when a path is diverted or is not entirely available for cars to drive on. The diversion may be due to hazards present due to the construction or for the safety for the construction workers. One must slow down when passing through such construction zones in order to prevent collisions and injuries.
Frame of reference refers to something that is not moving with respect to an observer that can be used to detect motion.
Answer:
Approximately 
.
Explanation:
<h3>Solve this question with a speed-time plot</h3>
The skateboarder started with an initial speed of 
and came to a stop when her speed became 
. How much time would that take if her acceleration is 
?
.
Refer to the speed-time graph in the diagram attached. This diagram shows the velocity-time plot of this skateboarder between the time she reached the incline and the time when she came to a stop. This plot, along with the vertical speed axis and the horizontal time axis, form a triangle. The area of this triangle should be equal to the distance that the skateboarder travelled while she was moving up this incline until she came to a stop. For this particular question, that area is approximately equal to:
.
In other words, the skateboarder travelled 
up the slope until she came to a stop.
<h3>Solve this question with an SUVAT equation</h3>
A more general equation for this kind of motion is:
,
where:
and 
are the initial and final velocity of the object,
is the constant acceleration that changed the velocity of this object from to , and
is the distance that this object travelled while its velocity changed from to .
For the skateboarder in this question:
.
Answer:
b) G.P.E = Mgh
300j = M x 10 m/s² x 15 m
300 j/ 10 m/s² x 15 m = M
300j/ 150 s² = M
2kg = M
c) K.E = 1/2 m v²
K.E = 1/2 (50) (50)²
K.E = 1/2 (50) (2500)
K.E= 125000/2
K.E = 625 000 J
