Answer:
A. Her speed is 4.4 m/s, and her velocity is 0 m/s.
Explanation:
Given parameters:
Length of path = 400m
Time taken = 6min = 360s
Unknown:
Speed and velocity = ?
Solution:
Velocity is the displacement divide by the time. Displacement takes into the account the distance covered with specific reference to direction. Since the student started and ended the journey on the same spot, the net displacement is 0.
So,
Since velocity =
Velocity = 0
Speed is the distance divided by time;
One lap = 400m,
four laps = 400 x 4 = 1600m
Speed = = 4.4m/s
Answer:
180 W
Explanation:
The work done by the man against gravity is equal to its gain in gravitational potential energy:
where
(mg) = 720 N is the weight of the man
is the change in height
Substituting,
The power he must deliver is given by
where
W = 3600 J
t = 20 s is the time taken
Substituting,
Answer:
468 m
Explanation:
So the building and the point where the laser hit the water surface make a right triangle. Let's call this triangle ABC where A is at the base of the building, B is at the top of the building, and C is where the laser hits the water surface. Similarly, the submarine, the projected submarine on the surface and the point where the laser hit the surface makes a another right triangle CDE. Let D be the submarine and E is the other point.
The length CE is length AE - length AC = 284 - 234 = 50 m
We can calculate the angle ECD:
This is also the angle ACB, so we can find the length AB:
So the height of the building is 468m