To solve this problem we will apply the concepts related to the conservation of the Momentum. For this purpose we will define the momentum as the product between mass and velocity, and by conservation the initial momentum will be equal to the final momentum. Mathematically this is,
Here,
= Mass of Dan and Skateboard respectively
= Initial velocity of Dan and Skateboard respectively
= Final velocity of Dan and Skateboard respectively
Our values are:
Dan's mass
Mass of the skateboard
Both have the same initial velocity, then
Final velocity of Skateboard is
Rearranging to find the final velocity of Dan we have then,
Replacing,
Therefore Dan will touch the ground at a speed of 3.76m/s
Answer:
vx = 65 yd/3 sec = 21.7 yd/sec since horizontal speed is constant
vy = g t = (32 / 3) yd/sec^2 * 1.5 sec = 16 yd/sec where 32/3 is the acceleration due to gravity in yds / sec^2 and 1.5 is the time to travel each way in the vertical direction
V = (vx^2 + vy^2)^1/2 = (21.7^2 + 16^2)^1/2 = 27 yd/sec
tan theta = vy/vx = 16 / 21.7 = .737 theta = 36.4 deg
You can check using the range formula:
R = v^2 sin (2 theta) / g = 27^2 * .955 / (32 / 3) = 65.3 yds
The difference from 65 yds may be rounding error.
I think that it is a mixture because air can contain anything.
Answer:
The answer would be A. The waves that heat a cup of water in a microwave oven
