Answer:
The new speed of the ball is 176.43 m/s
Explanation:
Given;
mass of the ball, m = 7 kg
initial speed of the ball, u = 5 m/s
applied force, F = 300 N
time of force action on the ball, t = 4 s
Apply Newton's second law of motion;
where;
v is new speed of the ball
Therefore, the new speed of the ball is 176.43 m/s
The answer is c. Moving Water
The sample appears to have gone through 3 half-lives
1st half life: 1000 to 500 g
2nd half life: 500 to 250 g
3rd half life: 250 to 125 g
The duration of a half-life, therefore, can be inferred to be 66 ÷ (3) = 22 days.
After a 4th half life, there will be 125÷2= 62.5 g.
At this point, an additional 22 days will have passed, for a total of 88 days.
Answer is C.
Answer:
The work-energy theorem states that a force acting on a particle as it moves over a <u>distance</u> changes the <u>kinetic</u> energy of the particle if the force has a component parallel to the motion.
Explanation:
The correct answer is presented below and all reasons are presented to explain all facts:
The work-energy theorem states that a force acting on a particle as it moves over a <u>distance</u> changes the <u>kinetic</u> energy of the particle if the force has a component parallel to the motion.
Reasons:
According to the Work-Energy Theorem, the work done on a particle () equals the change in its kinetic energy (). That is:
(1)
By definition of work we expand this definition:
(2)
Where:
- Vector force.
- Vector travelled distance.
And by definition of dot product we conclude that:
Where:
- Magnitude of the vector force.
- Magnitude of the differential of the vector travelled distance.
- Angle between vectors, measured in sexagesimal degrees.
- Initial and final position of the particle.
From this expression we infer that change in kinetic energy is maximum if and only if in every point of the path travelled by the particle. In addition, change in kinetic energy occurs when component of force parallel to path is not zero.
The law of conservation of energy states that energy is neither created nor destroyed, but can be converted from one form to another.
When the book was at the shelf, its kinetic energy was zero and its potential energy was maximum. As it fell, its potential energy stated converting to kinetic energy. Before the book directly hits the ground, its kinetic energy is maximum and its potential energy is zero.
Based on the above explanation, at the moment the book landed on the floor, ALL the potential energy was converted to kinetic energy, so the kinetic energy = 67 Joules.