Answer: 4 s
Explanation:
Given
The applied force is 70 N
mass of the rock is 28 kg
initial velocity 
final velocity 
Deceleration provided by force is

using the equation of motion

Answer:
30.96 m
Explanation:
If the particle has a lifetime of 129 ns as measured by observer A, and has a speed of 0.8c as measured by observer A, the distance between the markers will be:
d = v * Δt
v = 0.8*c = 0.8 * 3e8 = 2.4e8
Δt = ζ = 129 ns = 1.29e-7 s
d = 2.4e8 * 1.29e-7 = 30.96 m
This is the distance as measured by observer A.
Answer:
its constant i think
Explanation:
or its stable dunno which term will they be using
Sound source is at rest, you are moving with velocity v, f = frequency, c = speed of sound:
f = f0(1 + v/c)
115 = 100(1 + v/343)
115 = 100 + 100v/343
15 = 100v/343
v = 15*343/100
<span>
v = 51,45 m/s </span>
.... I don’t know but, he will be able to make smarter choices, he will be able to think before he does something, honestly don’t know