d(t) = 1.1t² + t + 1
The constant speed required to cover the same distance between t = 3 to t = 5 is the same as the average speed over that same time interval. It is given by:
v = Δx/Δt
v = average speed, Δx = change in distance, Δt = elapsed time
Given values:
Δx = d(5) - d(3) = 19.6ft
Δt = 5s - 3s = 2s
Plug in and solve for v:
v = 19.6/2
v = 9.8ft/s
The separation between them is 
Concept :
If the force increases, distance between charges must decrease. Force is indirectly proportional to the distance squared.
Given,
Two point charges are brought closer together, increasing the force between them by a factor of 20.
Original force is
F = 
-------- ( 1 )
Here, 
are charges and r is the distance between them
New force F' = 
----------- (2 )
Divide ( 1 ) and ( 2 )
= 
20 = 
r' =
Given that force between them are increasing and therefore distance between them decrease by
Learn more about two point charges here : brainly.com/question/24206363
#SPJ4
<h2>
Answer: B) It would be best to use a concave mirror, with the object to be ignited positioned halfway between the mirror and its center of curvature. </h2>
Explanation:
To start a fire it is more optimal to use a concave mirror than a plane mirror. This is because the concave mirror allows concentrating sunlight at a point (the focal point) on an object that acts as fuel and ignite the fire there.
For this it is necessary the object to be positioned between the center of curvature of the mirror and the mirror (its focus). Thus the rays of the Sun, when converging on the focus, will heat the object and make it burn.
Hence, the correct option is B.
The Continental crust is also less dense than oceanic crust, though it is considerably thicker; mostly 35 to 40 km versus the average oceanic thickness of around 7-10 km. About 40% of the Earth's surface is now underlain by continental crust.
