Answer:
At 11.5 m
Explanation:
The power per unit area corresponds to the intensity, which is given by
where
P is the power
is the area irradiated at a distance r from the source (it corresponds to the surface area of a sphere of radius r)
Here we want the intensity of the two light bulbs to be the same, so
where we have
P1 = 100 W is the power of the first light bulb
P2 = 75 W is the power of the second light bulb
r2 = 10 m is the distance from the second light bulb
Solving for r1, we find
Answer:
a)
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
a = Acceleration
The acceleration of the bicycle and rider is -1.5 m/s²
Force
The magnitude of the average force needed to bring the bicycle and its rider to a stop is
Answer:
31.75 m/s
Explanation:
h = 41.7 m
Let the initial velocity of the second stone is u
Let the time taken to reach to the bottom by the first stone is t then the time taken by the second stone to reach the ground is t - 1.8.
For first stone:
Use second equation of motion
Here, u = 0, g = 9.8 m/s^2 and t be the time and h = 41.7
So, 41.7= 0 + 0.5 x 9.8 x t^2
41.7 = 4.9 t^2
t = 2.92 s ..... (1)
For second stone:
Use second equation of motion
Here, g = 9.8 m/s^2 and time taken is t - 1.8 = 2.92 - 1.8 = 1.12 s, h = 41.7 m and u be the initial velocity
.... (2)
By equation the equation (1) and (2), we get
u = 31.75 m/s