Answer:
t = 7 sec.
Explanation:
As the car and the truck travel the same distance, assuming a constant acceleration, we can describe the movement of the truck and the car with these equations for this same displacement:
x(truck) = v*t (1)
x(car) = 
As the left sides of (1) and (2) are equal each other, the same must be true for the right sides:
v*t =
Solving for t, replacing v= 10.5 m/s and a= 3 m/s², we have:

⇒ t = 7 sec.
Power is the rate of doing work or using energy.
The unit of power is the watt.
1 watt = 1 joule per second
Answer:
A real emf device has an internal resistance, but an ideal emf device does not.
Answer
we know,

where
E = energy
h = planks constant
λ = wavelength
from the above equation, we can see that energy is inversely proportional to wavelength.

that is why
Violet color light has low wavelength but the energy of Violet light is very high whereas red light has low energy and high wavelength.