Answer:
Explanation:
Let h be the height .
initial velocity in first case u = 0
final velocity v = 6 m /s
acceleration due to gravity g = 9.8 m /s²
v² = u² + 2 g h
6² = 0 + 2 x 9.8 x h
h = 1.837 m .
For second case u = 3 m /s
v² = u² + 2 gh
= 3² + 2 x 1.837 x 9.8
= 9 + 36
= 45 m
v = 6.7 m /s
Answer:
a) t = 1.6 s
b) d = 4.9 m
c) v = 16 m/s
d) θ = 79°
Explanation:
time of fall
t = √(2h/g) = √(2(12)/9.8) = 1.5649... s
d = vt = 3.1(1.56) = 4.8512...
vertical velocity vy = at = 9.8(1.56) = 15.336... m/s
v = √(15.336² + 3.1²) = 15.6464... m/s
θ = arctan(15.336/3.1) = 78.5724...°
B.waves of light carry energy directly to your skin.
Explanation:
a. The net force is the upward force of the chute minus the weight of the crate.
∑F = F − mg
∑F = 150 N − (11 kg) (9.8 m/s²)
∑F = 42.2 N
b. From Newton's second law, the net force equals the mass times acceleration:
∑F = ma
42.2 N = (11 kg) a
a = 3.84 m/s²
c. Acceleration is the change in velocity over change in time. Assuming the crate is released from rest:
v = at + v₀
v = (3.84 m/s²) (5 s) + (0 m/s)
v = 19.2 m/s
Relative to the floor it's resting on, its height is zero,
so its potential energy is zero.
Relative to the next floor down, its height could be
three or four meters, and it could have plenty of
potential energy ... if you cut out a circle in the floor
all around the rock, and let it fall to next floor down,
it could really do some damage. Look out below ! !
