Question

2nd time asking for help please

Answer 1

Answer:

A. PE=360KJ   KE=60KJ   and v=10m/s

B. PE=180KJ   KE=240KJ   and v=20m/s

C. PE=0J         KE=420KJ   and v=26.46m/s

D. PE=120KJ   KE=300KJ   and v=22.36m/s

E. PE=240KJ   KE=180KJ    and v=17.32m/s

1. 360KJ.

2.12KW

3.The total energy is equal at every point, by conservation of energy.

4.Kinetic energy is greatest at point C, and so is velocity. It makes sense for  KE to become greater as v becomes greater since the formula for KE shows that kinetic energy is a product of velocity and weight.

5. As PE lowers, KE grows and vice versa since due to the conservation of momentum, energy cant 'die' or disappear, it can only be changed into a new form of energy.

Step-by-step explanation:

First off: Potential energy=mgh, where m is mass, g is acceleration due to gravity and h is height. Kinetic energy=(1/2)mv², where m is mass again and v is velocity.

Let g=10m/s², let PE denote potential energy, let KE denote kinetic energy and let E denote total energy (PE+KE). Due to conversation of energy, the value of E will remain constant.

v, in terms of KE, is equal to √(2KE/m)

A

PE=mgh=(1200)(10)(30)=360,000J=360KJ

KE=(1/2)mv²=(1/2)(1200)(10²)=60,000J=60KJ

E=PE+KE=360,000+60,000=420,000J=420KJ

B

PE=mgh=(1200)(10)(15)=180,000J=180KJ

KE=E-PE=420,000-180,000=240,000J=240KJ

v=√(2KE/m)=√(2(240,000)/1,200)=√400=20m/s

C

PE=mgh=(1200)(10)(0)=0J

KE= E-PE = 420,000KJ=420KJ

v=√(2KE/m)=√(2(420,000)/1,200)=√700=26.4575131106≈26.46m/s

D

PE=mgh=(1200)(10)(10)=120,000J=120KJ

KE=E-PE=420,000-120,000=300,000J=300KJ

v=√(2KE/m)=√(2(300,000)/1,200)=√500=22.360679775=22.36m/s

E

PE=mgh=(1200)(10)(20)=240,000J=240KJ

KE=E-PE=420,000-240,000=180,000J=180KJ

v=√(2KE/m)=√(2(180,000)/1,200)=√300=17.3205080757=17.32m/s

1. The work done to go up to that point is equal to the potential energy at that point (force=mg, work=(force)(height), therefore work=mgh=PE). So the work done to get to A is the potential energy at A, which is 360KJ.

2.Power=work/time=360000/30=12000=12KW

3.The total energy is equal at every point, by conservation of energy.

4.Kinetic energy is greatest at point C, and so is velocity. It makes sense for  KE to become greater as v becomes greater since the formula for KE shows that kinetic energy is a product of velocity and weight.

5. As PE lowers, KE grows and vice versa since due to the conservation of momentum, energy cant 'die' or disappear, it can only be changed into a new form of energy.