The mass attached to the spring must be 0.72 kg
Explanation:
The frequency of vibration of a spring-mass system is given by:
(1)
where
k is the spring constant
m is the mass attached to the spring
We can find the spring constant by using Hookes' law:

where
F is the force applied on the spring
x is the stretching of the spring
When a mass of m = 2.82 kg is applied to the spring, the force applied is the weight of the mass, so we have

and using
and
, we find

Now we want the frequency of vibration to be
f = 7.42 Hz
So we can rearrange eq.(1) to find the mass m that we need to attach to the spring:

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Waves get their energy from the wind.
Answer:
t = 1.62 s
Explanation:
given,
mass of the block m₁ = 16.5 Kg
m₂ = 8 Kg
angle of inclination = 60°
μs = 0.400 and μk = 0.300
time to slide 2 m = ?
a) let a is the acceleration of the block m₁ downward.
Net force acting on m₂,
F₂ = T - m₂ g
m₂a = T - m₂ g
.......(1)
net force acting on m₁
F₁ = m₁g sin(60°) - μ_k m₁g cos (60°) - T
m₁ a = m₁g sin(60°) - μ_k m₁g cos (60°) - T
.........(2)
from equations 1 and 2





T = 90.61 N
from equation (1)
.......(1)
a = 1.52 m/s²
let t is the time taken
Apply,
d = ut + 0.5 a t²
2 = 0 + 0.5 x 1.52 x t²

t = 1.62 s