I think they are right! When one of the answers is, all of the above, that is usually the correct answer. pH is important to all living things.
Answer:
t = 1.15 + .713 = 1.863 [s]
Explanation:
To solve this problem we must use the following kinematic equation, but first we identify the initial data.
vo = 7 [m/s]
yo = 4 [m]
g = 9.81[m/s^2]
![v_{f}=v_{o}-g*t\\0 = 7 - (9.81*t)\\7 = 9.81*t\\t = 0.713[s]](https://tex.z-dn.net/?f=v_%7Bf%7D%3Dv_%7Bo%7D-g%2At%5C%5C0%20%3D%207%20-%20%289.81%2At%29%5C%5C7%20%3D%209.81%2At%5C%5Ct%20%3D%200.713%5Bs%5D)
The final velocity happens at the moment when the maximum height is reached, at this point the final speed is zero.
![y=y_{o}+v_{o}*t-0.5*g*t^{2}\\ y = 0+ (7*0.713)-0.5*9.81*(0.713)^{2}\\ y = 2.5[m]](https://tex.z-dn.net/?f=y%3Dy_%7Bo%7D%2Bv_%7Bo%7D%2At-0.5%2Ag%2At%5E%7B2%7D%5C%5C%20y%20%3D%200%2B%20%287%2A0.713%29-0.5%2A9.81%2A%280.713%29%5E%7B2%7D%5C%5C%20y%20%3D%202.5%5Bm%5D)
The total elevation will be 2.5 + 4 = 6.5 [m]
Now using again the total height we can find the final velocity.
![v_{f}^2=v_{o}^2+2*g*y\\v_{f}=\sqrt{2*g*y}\\ v_{f}=\sqrt{2*9.81*6.5}\\ v_{f}=11.3[m/s]](https://tex.z-dn.net/?f=v_%7Bf%7D%5E2%3Dv_%7Bo%7D%5E2%2B2%2Ag%2Ay%5C%5Cv_%7Bf%7D%3D%5Csqrt%7B2%2Ag%2Ay%7D%5C%5C%20v_%7Bf%7D%3D%5Csqrt%7B2%2A9.81%2A6.5%7D%5C%5C%20v_%7Bf%7D%3D11.3%5Bm%2Fs%5D)
With this final velocity we cand find the time.
![v_{f}=v_{i}+g*t\\11.3=0+9.81*t\\11.3=9.81*t\\t=1.15[s]](https://tex.z-dn.net/?f=v_%7Bf%7D%3Dv_%7Bi%7D%2Bg%2At%5C%5C11.3%3D0%2B9.81%2At%5C%5C11.3%3D9.81%2At%5C%5Ct%3D1.15%5Bs%5D)
Now we have to sum the two times, the time it takes to go up and the time it takes to go down.
t = 1.15 + .713 = 1.863 [s]
Answer: heat
Insulation Traps Heat. Keeping the cold air out
Explanation:
The strength of the gravitational force between two objects depends on two factors, mass and distance. the force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. increases, the force of gravity decreases.