A person throws a baseball from height of 7 feet with an initial vertical velocity of 50 feet per second. Use the vertical motio
2 answers:
Answer:
3.25 seconds
Explanation:
It is given that,
A person throws a baseball from height of 7 feet with an initial vertical velocity of 50 feet per second. The equation for his motion is as follows :
Where
s is the height in feet
For the given condition, the equation becomes:
When it hits the ground, h = 0
i.e.
It is a quadratic equation, we find the value of t,
t = 3.25 seconds and t = -0.134 s
Neglecting negative value
Hence, for 3.25 seconds the baseball is in the air before it hits the ground.
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Answer:
Mechanical energy, U = 0.247 Joules
Explanation:
Given that,
Spring constant of the spring, k = 234 N/m
Mass, m = 524 g = 0.524 kg
Amplitude, A = 4.6 cm = 0.046 m
To find,
The mechanical energy of the system.
Solution,
We know that the sum of kinetic energy and the potential energy is equal to its mechanical energy. In mass-spring system, it is given by :
U = 0.247 Joules
So, the mechanical energy of the system is 0.247 Joules.
Answer:
The kinetic energy of the phone would increase. The gravitational potential energy of the phone would decrease.
Explanation:
The kinetic energy of an object is proportional to the square of the speed of that object. If air resistance is negligible, the phone would accelerate under gravitational pull and speed up. Hence, the kinetic energy of the phone would increase.
The gravitational field near the surface of the earth is approximately constant. Hence, the gravitational potential energy of the phone would be proportional to its height. As the phone approaches the ground, the height of the phone becomes lower and the gravitational potential energy of the phone would decrease.