I am assuming this is a true or false question, to which the answer would be True.
Since this is a distance/time graph, the speed at any time is the slope
of the part of the graph that's directly over that time on the x-axis.
At time t1 = 2.0 s
That's in the middle of the first segment of the graph,
that extends from zero to 3 seconds.
Its slope is 7/3 . v1 = 7/3 m/s .
At time t2 = 4.0 s
That's in the middle of the horizontal part of the graph
that runs from 3 to 6 seconds.
Its slope is zero.
v2 = zero .
At time t3 = 13 s.
That's in the middle of the part of the graph that's sloping down,
between 11 and 16 seconds.
Its slope is -3/5 . v3 = -0.6 m/s .
Answer:

Explanation:
If
-
,
are temperatures of gasses and liquid in Kelvins,
and
are thicknesses of gas layer and steel slab in meters,
,
are convection coefficients gas and liquid in
,
is the contact resistance in
,
- and
are thermal conductivities of gas and steel in
,
then: part(a):

using known values:
part(b): Using the rate equation :
the surface temperature 
and 
Similarly


The temperature distribution is shown in the attached image
W=Fd. Force is not given so we solve for it. F=ma, m=5kg, a=2m/s^2, F=10N. Distance is not given so we solve for it, x=.5a(t^2)=.5(2)(7x7)=49m. F=10N, d=49m, W=490J.
The net force of the cart when it is pushed to the right with a force of 15N.
<u>Explanation:</u>
To find the force of net, which is calculated by the formula.
The Net Force= Addition of the force applied on the respective direction.
The Net Force here is given by
The Net Force = 15-20 (A force towards the right and a force towards left, two opposite so subtraction).
Hence
Thus the Net Force = -5(The force towards left, so it gets a negative value).