Answer:
4 kg
Explanation:
momentum = mass x velocity
10 x 20 = 200
200 / 50 = <u>4</u>
Answer:
A. 3.3 m
Explanation:
Here, we have to use conservation of energy principle.
When the ball is at maximum height, the instantaneous velocity at that point is 0 m/s. So, the kinetic energy of the ball is also 0 at the maximum height. Thus, at maximum height, the energy possessed by the ball is gravitational potential energy only.
Now, when the ball reaches the ground, all the gravitational potential energy changes into kinetic energy because of the conservation of energy.
Therefore, the energy transformation can be given as:
Decrease in potential energy = Increase in Kinetic energy
Decrease in potential energy is given as:
Increase in kinetic energy is given as:
Therefore,
Now, plug in 8 for , 9.8 for and solve for height . This gives,
Therefore, the maximum height reached by the ball is 3.3 m.
I'll just find out the path difference between the waves at the starting point. At infinity, the path difference will be zero because the observer will be infinitely far away from both. As the observer goes farther, the path difference keeps reducing till it reaches zero as the observer reaches infinity.
<span>Path difference at starting point = Distance from lower speaker - Distance from upper speaker = √((3)² + (2.5)²) - 2.5 = 1.405 m </span>
<span>Now to find wavelength. </span>
<span>Speed of sound in air at 20 degrees C = 343 m/s </span>
<span>Wavelength = 343 / 686 = 0.5 m </span>
<span>Destructive interference occurs when path difference = (2n + 1)λ/2 where n is an integer. </span>
<span>Maximum n possible can be found by, </span>
<span>(2n + 1)λ/2 < 1.405 </span>
<span>(2n + 1) < (1.4)(2) / (0.5) </span>
<span>2n < 5.6 - 1 </span>
<span>2n < 4.6 </span>
<span>n < 2.3 </span>
<span>So, we have 3 values of n, 0, 1 and 2. </span>
<span>Path differences are, λ/2, 3λ/2 and 5λ/2 which have values 0.25 m , 0.75 m and 1.25 m </span>
<span>But the question asks for distance from starting point. (sheesh!!) </span>
<span>Lets say the observer walked x distance. </span>
<span>Path difference = √((3)² + (2.5 + x)²) - (2.5 + x) </span>
<span>Equate this expression to the values obtained above to get the different values of x. </span>
Both balls land at the same time. If there is no air resistance they will both accelerate at the same rate and hit the ground at the same time with the same speed.