Answer:
The two forces acting on the object are weight due to gravity pulling the object towards earth, and drag resisting this motion. When the object is first released, drag is small as velocity is low, so the resultant force is down. This means the object accelerates towards earth.
Answer:
A. 148.23 m
B. 2.75 m/s
Explanation:
The following data were obtained from the question:
Time of flight (T) = 11 s
Maximum height (h) =?
Initial velocity (u) =?
Next, we shall determine the time taken for the ball to get to the maximum height. This can be obtained as follow:
Time of flight (T) = 11 s
Time (t) to reach the maximum height =.?
T = 2t
11 = 2t
Divide both side by 2
t = 11/2
t = 5.5 s
NOTE: Time to reach the maximum height is the same as the time taken for the ball to fall back to the plane of projection.
A. Determination of the maximum height to which the ball was thrown.
Time (t) to reach maximum height = 5.5 s
Acceleration due to gravity (g) = 9.8 m/s²
Maximum height (h) =?
h = ½gt²
h = ½ × 9.8 × 5.5²
h = 4.9 × 30.25
h = 148.23 m
B. Determination of the initial velocity.
Maximum height (h) reached = 148.23 m
Acceleration due to gravity (g) = 9.8 m/s²
Initial velocity (u) =?
u² = h/2g
u² = 148.23 / (2 × 9.8)
u² = 148.23 / 19.6
Take the square root of both side
u = √(148.23 / 19.6)
u = 2.75 m/s
The slope of the distance/time graph is the speed of the moving object.
So the graph for a fast moving object will have a greater slope than the
graph for a slower moving object has.
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.