Answer:
I believe the answer is B.)
To break this problem down, let's start with what we know. The equation given finds one component of the velocity and multiplies it by the change in time. This will not find the acceleration that the first two answers say it will, meaning that the answer isn't A or B.
That leaves us with the final two answers, C and D. If the projectile was launched horizontally and we were trying to find the horizontal displacement, we wouldn't need to use cosθ to find the horizontal velocity, meaning that our answer is most likely C) <span>the horizontal displacement of a projectile launched at an angle!</span><span />
Answer:
2 s, -20 m/s
Explanation:
Given:
y₀ = 20 m
y = 0 m
v₀ = 0 m/s
a = -9.8 m/s²
Find: t and v
y = y₀ + v₀ t + ½ at²
0 = 20 + 0 + ½ (-9.8) t²
0 = 20 − 4.9 t²
t ≈ 2 s
v² = v₀² + 2a(y − y₀)
v² = 0 + 2(-9.8)(0 − 20)
v ≈ ±20 m/s
Since the rock is falling, v = -20 m/s.
Answer:
4 Newton
Explanation:
F=ma therefore 2kg*2m/s/s=4 Newton
