Answer:
B) 3.50 m/s
Explanation:
The linear velocity in a circular motion is defined as:

The angular frequency (
) is defined as 2π times the frequency and r is the radius, that is, the distance from the center of the circular motion.

Replacing (2) in (1):

We have to convert the frequency to Hz:

Finally, we calculate how fast is the child moving:

They are both used to observe and describe matter.
Answer:
Acceleration 
Explanation:
We have given that the force by the motor 
Resistive force by the water 
So net force 
Mass of the boat = 1384.1 kg
According to newton's second law F=Ma, here M is mass and a is acceleration
So 

Answer:
This is an incomplete question. The complete question is --
An individual white LED (light-emitting diode) has an efficiency of 20% and uses 1.0 W of electric power.
How many LEDs must be combined into one light source to give a total of 3.8W of visible-light output (comparable to the light output of a 100W incandescent bulb)?
And the answer is --
19 LEDs
Explanation:
The full form of LED is Light emitting diode.
It is given that the efficiency of the LED bulb is 20 %
1 LED uses power = 1 W
So the output power of 1 LED = 0.2 W
We need to find the power required to give a 3.8 W light.
Power required for 3.8 W = Number of LEDs required = (total required power / power required for 1 LED )
= 3.8 / 0.2
= 19
Therefore, the number of LEDs required is 19.