Answer:
a) t = 1.47 h b) t = 1.32 h
Explanation:
a) In this problem the plane and the wind are in the same North-South direction, whereby the vector sum is reduced to the scalar sum (ordinary). Let's calculate the total speed
v =
f -
v = 585 -32.1
v = 552.9 km / h
We use the speed ratio in uniform motion
v = x / t
t = x / v
t = 815 /552.9
t = 1.47 h
b) We repeat the calculation, but this time the wind is going in the direction of the plane
v=
f -
v 585 + 32.1
v = 617.1 km / h
t = 815 /617.1
t = 1.32 h
(20 miles) x ( 1/45 hour/mile) =
(20/45) (hour) = <em>
4/9 hour = </em>26 minutes 40 seconds
Answer: 91.4 J
Explanation:
Kinetic energy is the energy possessed by a body due to virtue of its motion.
K.E. = 0.5 m v²
Mass of the continent is given, m = 1.819 × 10²¹ kg
Side of the block of continent, s = 4150 km = 4150000 m
Depth of the block of continent, d = 38 km = 38000 m
(Mass = density × volume
m = 2780 kg/m³× (4150 × 10³ m)²× 38 × 10³ m = 1.819 × 10²¹ kg)
The continent is moving at the rate of, v = 1 cm /year = 0.01 m / 31556926 s = 3.17 × 10⁻¹⁰ m/s
⇒ K.E. = 0.5 × 1.819 × 10²¹ kg × (3.17 × 10⁻¹⁰ m/s)²= 91.4 J
Hence, mass of the continent has 91.4 J of kinetic energy.