Answer:
1.03 seconds
Explanation:
x = x₀ + v₀ t + ½ at²
0 = 7.63 + (-2.40) t + ½ (-9.8) t²
0 = 7.63 - 2.40 t - 4.9 t²
Solve with quadratic formula:
t = [ -b ± √(b² - 4ac) ] / 2a
t = [ 2.40 ± √(2.40² - 4(-4.9)(7.63)) ] / -9.8
t = -1.52, 1.03
Since t can't be negative here, the sandbag hits the ground after 1.03 seconds.
It would be the first one and the third one
Answer:
option (e) is correct.
Explanation:
mass of adult, M = 81 kg
Gravitational Potential energy of adult, U = 2000 J
Let the height raised is h.
U = mass of adult x g x h
2000 = 81 x 9.8 x h
h = 2.52 m
mass of adult, m = 18 kg
height raised, h = 2.52 m
Potential energy of child, U' = m x g x h
U' = 18 x 2.52 x 9.8 = 444.44 J
Thus, option (e) is correct.
Answer:
-10 m/s²
Explanation:
Average acceleration is change in velocity over change in time.
a = (v − v₀) / (t − t₀)
a = (0 m/s − 20 m/s) / (2 s − 0 s)
a = -10 m/s²