Answer:
1) at the highest Point
KE= 0 PE=2116.8 N
2) 3 m above the ground
PE= 529.2 N KE=1587.6 N
3) at the ground
KE= 2116.8 N and PE=0
Explanation:
The potential energy is given by
PE= mgh where m is the mass , g is the acceleration due to gravity which is equal to 9.8 m/s² and h is the height.
The kinetic energy is given by KE= 1/2 mv² where m is the mass of the body and v is the velocity.
1) at the highest Point
Now at the highest point the velocity is zero
KE= 1/2 mv²
KE= 0
PE = mgh
PE= 18 *9.8* 12= 2116.8 N
Total Energy = KE + PE= 0 + 2116.8 N= 2116.8 N
2) 3 m above the ground
At 3 m above the ground
PE= mgh
PE= 18 *9.8* 3= 529.2 N
According to law of conservation of energy the total energy ( sum of KE and PE) remains the same at every point.
Total Energy = KE + PE
2116.8 N-529.2N= 1587.6N
KE=1587.6 N
3) at the ground
at the ground the height will be zero
PE= mgh
PE= 18 *9.8* 0= 0 N
According to law of conservation of energy the total energy ( sum of KE and PE) remains the same at every point.
Total Energy = KE + PE
2116.8 N=2116.8 N + 0
KE= 2116.8 N
or
KE= 1/2 mv²
KE = 1/2* 18 *(15.36)²= 2116.8