STEP ONE:
Let you and your friend stand as far away as possible from a large reflecting wall and clap your hands rapidly at a regular rate.
STEP TWO:
Adjust this rate until each clap just coincides with the return of an echo of its predecessor, or until clap and echo are heard as equally spaced.
STEP THREE:
Use a stopwatch to find the time between claps, t. Make a rough measurement of distance to the wall, s. Thus the speed of sound, v = 2s/t
Answer:
a) 1.725*10^5 N
b) 3.83*10^3 N
c) i) 173.24 kN
c) ii) 4.57 kN
Explanation:
See the attachment for calculations
Mass of the block = 1.4 kg
Weight of the block = mg = 1.4 × 9.8 = 13.72 N
Normal force from the surface (N) = 13.72 N
Acceleration = 1.25 m/s^2
Let the coefficient of kinetic friction be μ
Friction force = μN
F(net) = ma
μmg = ma
μg = a
μ = 
μ = 
μ = 0.1275
Hence, the coefficient of kinetic friction is: μ = 0.1275
Please elaborate more on your question so I can help you
2 is the answer have a nice day <3