Answer: The first one is A and C
Explanation:
If during an process no flow of heat takes place from system to surrounding for example isolated system then it said to be adiabatic process
<span> = r x F </span>
<span>| τ | = | r x F | = | r | | F | sinΘ </span>
<span>100 = | (0.3)<0, 1, 0> x (F/5)<0, 3, -4> | </span>
<span>5000/3 = | F | | <0, 1, 0> x <0, 3, -4> | </span>
<span>5000/3 = | F | | <-4, 0, 0> | </span>
<span>5000/3 = | F | * 4 </span>
<span>| F | = 1250/3 </span>
<span>| F | = 417 N </span>
<span>Check: </span>
<span>τ = r x F </span>
<span>100<-1, 0, 0> = 0.3<0, 1, 0> x 250/3<0, 3, -4> </span>
<span>100<-1, 0, 0> = 25 ( <0, 1, 0> x <0, 3, -4> ) </span>
<span>100<-1, 0, 0> = 25 ( <-4, 0, 0> ) </span>
<span>100<-1, 0, 0> = 100<-1, 0, 0> </span>
<span>What the other people forgot was that you need the angle from the y-axis, which would be Θ = arctan(O/A) = arctan(z/y) = arctan(-4/3) = -53.1°. Then you take the sine of that to get 0.8. There is more work being done on the z-vector than there is on the y-vector, so the force is distributed (0.6) in the y-direction, and (0.8) in the z-direction (0.6² + 0.8² = 1). </span>
For this case we have the following equation:
h (t) = -16t ^ 2 + 36t + 36
By the time the rock hits the water we have:
-16t ^ 2 + 36t + 36 = 0
Solving the second degree polynomial we have:
t1 = -3/4
t2 = 3
We discard the negative root because we want to find the time.
Answer:
It will take for the rock to hit the water about:
t = 3 seconds