<h2>
<u>KINETIC ENERGY</u></h2>
<h3>Problem:</h3>
» A 2kg mass is moving at 3m/s. What is its kinetic energy?
<h3>Answer:</h3>
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<h3>Formula:</h3>
To calculate the velocity of a kinetic energy, we can use formula
where,
- v is the velocity in m/s
- KE is the kinetic energy in J (joules)
- m is the mass in kg
— — —
Based on the problem, the givens are:
- KE (Kinetic energy) = ? (unknown)
- m (mass) = 2 kg
- v (velocity) = 3 m/s
<h3>Solution:</h3>
To get the velocity, substitute the givens in the formula above then solve.
Therefore, the kinetic energy is 9 Joules.
Answer:
-100N
Explanation:
Newton's third law of motion states that to every force exerted on one body, there is an equal and opposite force. This means that if object A exerts an ACTION force on B, there is a force called REACTION FORCE, which is equal and opposite, exerted on A by B.
The action and reaction forces are equal in size/magnitude but opposite in direction. In this case where a tennis racket strikes a tennis ball with a force (action force) of 100N, the ball will strike the racket with a reaction force of -100N.
F(RB) = -F(BR)
Given that,
Initial velocity , Vi = 0
Final velocity , Vf = 40 m/s
Acceleration due to gravity , a = 9.81 m/s²
Distance can be calculated as,
2as = Vf² - Vi²
2 * 9.81 *s = 40² - 0²
s = 81.55 m
For half height, that is, s = 40.77m
Vf= ??
2as = Vf² - Vi²
2 * 9.81 * 40.77 = Vf² - 0²
Vf² = 800
Vf = 28.28 m/s
Therefore, speed of roller coaster when height is half of its starting point will be 28 m/s.
