Direction. Velocity is a vector that describes both speed and direction, while speed is a scalar that describes only speed regardless of direction.
Answer:
a) 
b) 
c) 
d) Displacement = 22 m
e) Average speed = 11 m/s
Explanation:
a)
Notice that the acceleration is the derivative of the velocity function, which in this case, being a straight line is constant everywhere, and which can be calculated as:

Therefore, acceleration is 
b) the functional expression for this line of slope 4 that passes through a y-intercept at (0, 3) is given by:

c) Since we know the general formula for the velocity, now we can estimate it at any value for 't", for example for the requested t = 1 second:

d) The displacement between times t = 1 sec, and t = 3 seconds is given by the area under the velocity curve between these two time values. Since we have a simple trapezoid, we can calculate it directly using geometry and evaluating V(3) (we already know V(1)):
Displacement = 
e) Recall that the average of a function between two values is the integral (area under the curve) divided by the length of the interval:
Average velocity = 
The reason why the snails are dead because the snails lack oxygen for it is a model of closed ecosystem. Another reason to this is that they lack abiotic factors that they need in surviving or as they live for the place that they are living lacks a lot and are not enough for them to last or survive. Lastly, the water could have not been a contributor for them to live for they may not be able to live in a water environment and could only dwell in land.
The speed of A and B immediately after collision is 5.28m/s
<u>Explanation:</u>
Mass of A is 6275kg
Speed of A is 6.5m/s
Mass of B is 5155kg
Speed of B is 3.8m/s
Track is frictionless.
A and B stick together.
speed of attached A and B = ?
mₐsₐ + mᵇsᵇ = (mₐ + mb) s

Therefore, The speed of A and B immediately after collision is 5.28m/s
Humans can not see any of the above with their eyes