The power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.
<h3>What is electrical power?</h3>
Electrical power is the rate at which electrical work is done.
- Electrical power = voltage × current
The LED is 75% efficient means that 75% of power dissipated by the LED is converted to light.
Total power dissipated = 5 × 2.5 = 12.5 Watts
- Work done = power × time (in seconds)
Work done = 12.5 × (1 × 3600 + 15 × 60)
Work done = 56250 J = 56.25 kJ
Therefore, the power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.
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Answer:
D) intermolecular attraction deceased
The restoring force on the spring is found to have exactly the same magnitude as the stretching force. Option D
<h3>What is the restoring force?</h3>
The restoring force is the force that seeks to restore the spring to its equilibrium position. It has the same magnitude as the stretching force but acts in opposite direction.
Thus, the restoring force on the spring is found to have exactly the same magnitude as the stretching force.
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Answer:
a) 8.58 m/s upward
b) -2.211 m/s downward
Explanation:
Let gravitational acceleration g = -9.81m/s2. This is negative because it deceleration the upward motion of the key.
(a)We have the following equation of motion

where
is the initial upward velocity of the keys, t = 1.1s is the time it takes for the keys to travel a distance of s = 3.5 m




So the keys were thrown initially upward with a speed of 8.58 m/s
(b) If the initial velocity of the key is 8.58 m/s and it is subjected to a deceleration of 9.81m/s2 for 1.1s then the velocity right at the 1.1s instant is

So they keys would have a downward speed of 2.211 m/s