Answer:
B. holding a coffee mug
Explanation:
Something must move a distance for work to be done.
That's wave 'diffraction'.
Answer:
180 Newton(N)
Explanation:
force =mass *acceleration
=60 * 3
=180 kgm/s^2
=180 N
Running on sand requires 1.6 times more energy spent than running on hard surface, so the force applied by our foot on sand is less.
The first thing you should know for this case is the definition of distance.
d = v * t
Where,
v = speed
t = time
We have then:
d = v * t
d = 9 * 12 = 108 m
The kinetic energy is:
K = ½mv²
Where,
m: mass
v: speed
K = ½ * 1500 * (18) ² = 2.43 * 10 ^ 5 J
The work due to friction is
w = F * d
Where,
F = Force
d = distance:
w = 400 * 108 = 4.32 * 10 ^ 4
The power will be:
P = (K + work) / t
Where,
t: time
P = 2.86 * 10 ^ 5/12 = 23.9 kW
answer:
the average power developed by the engine is 23.9 kW
