Answer:
a) t = 1second
b) KE = 1000Joules
Explanation:
According to equation of motion,
S = ut+1/2at² where
S is the distance or height of fall = 5m
u = initial velocity = 0m/s²
a = +g = acceleration due to gravity = 10m/s²
Substituting the values in the formula to get the time we have,
5 = 0+1/2(10)t²
5 = 5t²
t² = 1
t = 1second
Time taken by the stone to reach the ground is 1second
b) Kinetic energy is the energy possessed by a body by virtue if its motion.
KE = 1/2MV² where m is the mass of the body and v is the velocity.
Given mass = 20kg
To get the velocity, we will use the equation of motion,
v = u + at
v is the final velocity
u is the initial velocity = 0m/s
a = +g = 10m/s
t = time = 1second
v = 0+10(1)
v = 10m/s
KE = 1/2×20×10²
KE = 10×100
KE = 1,000Joules
