A flat screen tv uses 120 watts. How much energy is used up if it is left on for 15 min?
1 answer:
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Answer:
3.16 m·s⁻¹ at an angle of 71.6°
Explanation:
Assume that the diagram is like Fig. 1 below.
The boat is heading straight across the river and the current is directed straight downstream.
We have two vectors at right angles to each other.
1. Calculate the magnitude of the resultant
We can use the Pythagorean theorem (Fig. 2).
R² = (3 m·s⁻¹)² + (1 m·s⁻¹)² = 9 m²·s⁻² + 1 m²·s⁻² = 10 m²·s⁻²
R = √(10 m²·s⁻²) ≈ 3.16 m·s⁻¹
2. Calculate the direction of the resultant
The direction of the resultant is the counterclockwise angle (θ) that it makes with due East .
tanθ = opposite/adjacent = 3/1 = 3
θ = arctan 3 = 71.6°
To an observer at point O, the velocity of the boat is 3.16 m·s⁻¹ at an angle of 71.6°.
Answer:
The force of the car engine.
Explanation:
The work- energy theorem states that the work done on an object is equal to the change in its kinetic energy. Its expression is given by :
Also, W = F.d
Where
F is the force applied by the engine of car
d is the displacement
m is the mass of an object
u is the initial speed
v is the final speed
So, the force of the car engine increased the car’s kinetic energy. Hence, this is the required solution.