Radioactive decay is given by:
N = No x e^(-λt)
We know that N/No has to be 0.05
λ = 0.15
0.05 = e^(-0.15t)
t = ln(0.05)/(-0.15)
t = 19.97 days
Answer
given,
mass of ball = 5.93 kg
length of the string = 2.35 m
revolve with velocity of 4.75 m/s
acceleration due to gravity = 9.81 m/s²
T cos θ = mg
T cos θ = 
T cos θ = 58.17






T² - 56.93T - 3383.75 = 0
T = 93.22 N

θ = 51.39°
Answer:
When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object. For example, when energy is transferred to an Earth-object system as an object is raised, the gravitational field energy of the system increases. This energy is released as the object falls; the mechanism of this release is the gravitational force. Likewise, two magnetic and electrically charged objects interacting at a distance exert forces on each other that can transfer energy between the interacting objects.
Explanation:
Even when an object is sitting still, it has energy stored inside that can be turned into kinetic energy (motion). ... A force is a push or pull that causes an object to move, change direction, change speed, or stop. Without a force, an object that is moving will continue to move and an object at rest will remain at rest.
Answer:
<h3>0.445</h3>
Explanation:
In friction, the coefficient of friction formula is expressed as;

Ff is the frictional force = Wsinθ
R is the reaction = Wcosθ
Substitute inti the equation;

Given
θ = 24°

Hence the coefficient of kinetic friction between the box and the ramp is 0.445
Answer:
The maximum height the box will reach is 1.72 m
Explanation:
F = k·x
Where
F = Force of the spring
k = The spring constant = 300 N/m
x = Spring compression or stretch = 0.15 m
Therefore the force, F of the spring = 300 N/m×0.15 m = 45 N
Mass of box = 0.2 kg
Work, W, done by the spring =
and the kinetic energy gained by the box is given by KE = 
Since work done by the spring = kinetic energy gained by the box we have
=
therefore we have v =
=
=
= 5.81 m/s
Therefore the maximum height is given by
v² = 2·g·h or h =
=
= 1.72 m