Answers:
a) 
b) 
c) 
Explanation:
We have the following data:
is the spring constant
is the amplitude of oscillation
is the velocity of the block when
Now let's begin with the answers:
<h3>a) Mass of the block</h3>
We can solve this by the conservation of energy principle:
(1)
Where:
is the initial potential energy
is the initial kinetic energy
is the final potential energy
is the final kinetic energy
Then:
(2)
Isolating
:
(3)
(4)
(5)
<h3>b) Period</h3>
The period
is given by:
(6)
Substituting (5) in (6):
(7)
(8)
<h3>c) Maximum acceleration</h3>
The maximum acceleration
is when the force is maximum
, as well :
(9)
Being 
Hence:
(10)
Finding
:
(11)
(12)
Finally:

Answer:
The 80 mph car
Because the formula says 1/2 mass but for the velocity it is squared
ANSWER
T₂ = 10.19N
EXPLANATION
Given:
• The mass of the ball, m = 1.8kg
First, we draw the forces acting on the ball, adding the vertical and horizontal components of each one,
In this position, the ball is at rest, so, by Newton's second law of motion, for each direction we have,

The components of the tension of the first string can be found considering that they form a right triangle, where the vector of the tension is the hypotenuse,

We have to find the tension in the horizontal string, T₂, but first, we have to find the tension 1 using the first equation,

Solve for T₁,

Now, we use the second equation to find the tension in the horizontal string,

Solve for T₂,

Hence, the tension in the horizontal string is 10.19N, rounded to the nearest hundredth.
Precisely around 1,800 miles below.
C: if it senses unequal currents