1). one disadvantage as using it is because it covers far less space. this would make much more blind spots. 2. the advantage of them is that they don't lie about the distances. the current convex mirrors we have in out cars right now, is that the imagine might look father or closer than they appear, which can be troubling at times.
plan mirrors are flat, car mirrors are convex.
Answer:
Explanation:
Given
Initial velocity of ball 
height of window 
Using Equation of motion

where u=initial velocity
t=time
a=acceleration
As ball is already is at a height of 20 m so



(b)highest point is obtained at v=0

where
v=final velocity
u=initial velocity
a=acceleration
s=displacement



Highest Point will be 
(c)Time taken when the ball hit the ground i.e. at Y=0


impact velocity 
Explanation:
PE= mgh
6 J= (3m) (9.81 m/s2) (mass)
mass=( 6)/(3×9.81)
mass= 0.20 Kg
Answer:
6.22 N/m
Explanation:
From Hooke's law we deduce that F=kx where F is the applied force and k is the spring constant while x is the extension or compression of the spring. Making k the subject of the above formula then

We also know that the force F is equal to mg where m is the mass of an object and g is acceleration due to gravity hence substituting F with mg we get that

Substituting m with 425 g which is equivalent to 0.425 kg and g with 9.81 then 0.67 for x we get that

Therefore, the spring constant is approximately 6.22 N/m