Answer:
The focal length of the concave mirror is -15.5 cm
Explanation:
Given that,
Height of the object, h = 20 cm
Radius of curvature of the mirror, R = -31 cm (direction is opposite)
Object distance, u = -94 cm
We need to find the focal length of the mirror. The relation between the focal length and the radius of curvature of the mirror is as follows :
R = 2f
f is the focal length


f = -15.5 cm
So, the focal length of the concave mirror is -15.5 cm. Hence, this is the required solution.
Explanation:
KE =1/2 MV^2
HOPE YOU COULD SOLVE FROM NOW..
Answer:
a) v=2.743m/s
b) 
c) T=2.543N
Explanation:
First, calculate the height of the ball at the starting point:


At this point, just in the moment the ball is released, all the energy of the system is potencial gravitational energy. When it is at the bottom all the potencial energy is transformed into kinetic energy:

Solving for v:

if h is the height loss: (l-y')
v=2.743m/s
The centripetal acceleration is the acceleration caused by the tension force exercised by the string, and is pointing outside of the trayectory path (at the lowest point, directly dawn):


To calculate tension, just make the free body diagram of forces in the ball, noticing the existence of the centripetal acceleration:
