Answer:
1. True
2. False
3. True
Explanation:
Newton's 2nd law states that the net force exerted on an object is equal to the product between the mass of the object and its acceleration:
(1)
where
is the net force on the object
m is its mass
a is the acceleration
Furthermore, we know that acceleration is defined as the rate of change of velocity:

So let's now analyize the three statements:
1. A net force causes velocity to change: TRUE. Net force (means non-zero) causes a non-zero acceleration, which means that the velocity of the object must change.
2. If an object has a velocity, then we can conclude that there is a net force on the object: FALSE. The fact that the object has a velocity does not imply anything about its acceleration: in fact, if its velocity is constant, then its acceleration is zero, which would mean that the net force on the object is zero. So this statement is not necessarly true.
3. Accelerations are caused by the presence of a net force: TRUE. This is directly implied by eq.(1): the presence of the net force results in the object having a non-zero acceleration.
Momentum = (mass) x (speed)
If the speed is zero, then the momentum is zero.
<span>Boyle's Law, in short, states that the volume of a gas is inversely proportional to its pressure AS LONG AS THE TEMPERATURE REMAINS UNCHAnged </span>
Using the theorem of kinetic energy
1/2mVf² - 1/2mVi²= WF + Wp, Wp=0
WF = F. AB, AB=5m and F= 40N, m=20kg
so the final kinetic is KEf= 1/2mVf² = WF =<span>F. AB= 40*5=200J
</span>
the final velocity is 1/2mVf² <span>=200, implies Vf= sqrt(20)=2sqrt(5)m/s</span>