The mass of an object and how rough the surface is
Answer:
a) about 20.4 meters high
b) about 4.08 seconds
Explanation:
Part a)
To find the maximum height the ball reaches under the action of gravity (g = 9.8 m/s^2) use the equation that connects change in velocity over time with acceleration.
In our case, the initial velocity of the ball as it leaves the hands of the person is Vi = 20 m/s, while thw final velocity of the ball as it reaches its maximum height is zero (0) m/s. Therefore we can solve for the time it takes the ball to reach the top:
Now we use this time in the expression for the distance covered (final position Xf minus initial position Xi) under acceleration:
Part b) Now we use the expression for distance covered under acceleration to find the time it takes for the ball to leave the person's hand and come back to it (notice that Xf-Xi in this case will be zero - same final and initial position)
To solve for "t" in this quadratic equation, we can factor it out as shown:
Therefore there are two possible solutions when each of the two factors equals zero:
1) t= 0 (which is not representative of our case) , and
2) the expression in parenthesis is zero:
By firing electrons from a cathode gun at a known velocity through an electric field of a known strength, J.J Thomson was able to observe how much the field deflected the beam. With a mass-to-charge ratio calculated, he could determine that the mass of the electron was not significantly heavy (in fact almost nothing compared to the proton or neutron)
I do believe it is the third choice
In the same fluid, an object floats if its density is low enough, and it sinks if its density is high enough.
It doesn't matter which one is bigger, which one is smaller, how bitter or sweet the fluid is, what color the substances are, how much they cost, or what planet they came from.