A 10 kilogram object subjected to a 20 Newton force moves across a horizontal frictionless surface in the direction of the force. Before the force was applied, the speed of the object was 2.0 meters/second. When the force is removed the object is traveling at 6.0 meters per second. The initial kinetic energy is 20 J?
the kinetic energy = (1/2) m v^2
initially the speed is 2
so the initial Ke = (1/2)(10)(4) = 20 Joules
Now I suspect you will be asked what the final Ke is
(1/2)(10)(36) = 180 Joules
the increase in Ke = 180 - 20 = 160 Joules = work done by force
= Force*distance
so distance = 160/20 = 8 meters
now for time
Force * time = change in momentum
20 t = 10(6-2)
t = 40/20 = 2 seconds
To determine if the initial kinetic energy is 20 J, we can use the formula for kinetic energy:
Kinetic energy (KE) = (1/2) * mass * velocity^2
Given:
Mass (m) = 10 kg
Initial velocity (v1) = 2.0 m/s
Final velocity (v2) = 6.0 m/s
First, let's calculate the final kinetic energy using the formula:
KE2 = (1/2) * m * v2^2
KE2 = (1/2) * 10 kg * (6.0 m/s)^2
KE2 = 180 J
Since the object moves across a horizontal frictionless surface, no energy is lost due to friction. Therefore, the total initial kinetic energy (KE1) would be equal to the final kinetic energy (KE2).
KE1 = KE2
KE1 = 180 J
Hence, the initial kinetic energy is 180 J, not 20 J.
To determine if the initial kinetic energy is 20 J, we need to use the formula for kinetic energy:
Kinetic Energy (KE) = (1/2) * mass * velocity^2
Given:
Mass (m) = 10 kg
Initial velocity (u) = 2.0 m/s
Final velocity (v) = 6.0 m/s
We can calculate the final kinetic energy (KEf) first using the final velocity.
KEf = (1/2) * mass * velocity^2
= (1/2) * (10 kg) * (6.0 m/s)^2
= 180 J
Now, we can compare the final kinetic energy (KEf) with the given initial kinetic energy (KEi).
If the initial kinetic energy (KEi) is equal to 20 J, then KEf should also be equal to 20 J.
However, since KEf is not equal to 20 J (180 J ≠ 20 J), we can conclude that the initial kinetic energy is NOT 20 J.