Answer:
(a) 
(b)
Explanation:
It is given that,
Force acting on the particle, F = 12 N
Displacement of the particle, 
Magnitude of displacement, 
(a) If the change in the kinetic energy of the particle is +30 J. The work done by the particle is given by :

is the angle between force and the displacement
According to work energy theorem, the charge in kinetic energy of the particle is equal to the work done.
So,



(b) If the change in the kinetic energy of the particle is (-30) J. The work done by the particle is given by :


Hence, this is the required solution.
Answer:
air does not have a modulus of rigidity.
Explanation:
Since air is completely elastic medium, that is, it does not have a modulus of rigidity, therefore sound waves in air are longitudinal.
You can use Newton's Second Law which states:

Plug in given information:

This is closest to option
b which is your answer.
Answer:
the height (in feet) of the cliff is 121 ft
Explanation:
A stone hit the cliff with
speed, v = 88 ft/s
Acceleration, a= 32 ft/s^2
initial speed, u = 0 ft/s
height is h.
To solve this problem we will apply the linear motion kinematic equations, Equation of motion describes change in velocity, depending on the acceleration and the distance traveled
so, writing the formula of Equation of motion:
v^2 - u^2 = 2*a*h
substituting the appropriate values,
(88)^2 - 0 = 2*32* h
h=(88)^2 / 64
h= 121 ft
hence
the height (in feet) of the cliff is 121 ft
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Answer:
x = 6.94 m
Explanation:
For this exercise we can find the speed at the bottom of the ramp using energy conservation
Starting point. Higher
Em₀ = K + U = ½ m v₀² + m g h
Final point. Lower
= K = ½ m v²
Em₀ = Em_{f}
½ m v₀² + m g h = ½ m v²
v² = v₀² + 2 g h
Let's calculate
v = √(1.23² + 2 9.8 1.69)
v = 5.89 m / s
In the horizontal part we can use the relationship between work and the variation of kinetic energy
W = ΔK
-fr x = 0- ½ m v²
Newton's second law
N- W = 0
The equation for the friction is
fr = μ N
fr = μ m g
We replace
μ m g x = ½ m v²
x = v² / 2μ g
Let's calculate
x = 5.89² / (2 0.255 9.8)
x = 6.94 m