Three quick physics questions! Please help asap!As a rock falls without air resistance, which of the following is true?

The kinetic energy of the rock transforms into potential energy.

All the potential energy becomes kinetic energy at the instant it is dropped.

Part of the potential energy of the rock becomes kinetic energy during each part of the fall.

The potential energy of the rock has been transformed into thermal energy by the time the rock reaches the ground.

A 1,400 kg car is moving at 12 m/s when the driver stops the car. What increase

Question

Three quick physics questions! Please help asap!As a rock falls without air resistance, which of the following is true?
  
       The kinetic energy of the rock transforms into potential energy.

       All the potential energy becomes kinetic energy at the instant it is dropped.

       Part of the potential energy of the rock becomes kinetic energy during each part of the fall.

       The potential energy of the rock has been transformed into thermal energy by the time the rock reaches the ground.


A 1,400 kg car is moving at 12 m/s when the driver stops the car. What increase

roadjester · Answer

okay, please only post one question at a time

anonymous · Answer

I know and I'll do that next time but right now kinda need to do this fast

anonymous · Answer

I think for the first it should be the last option?

anonymous · Answer

@roadjester

roadjester · Answer

$$K=\frac 1 2 mv^2$$
$$U=mgy$$
Total energy = K+U;
Now think. You are becoming too dependent on others giving you the answer straight out.

anonymous · Answer

ok so it would be option d?

roadjester · Answer

you said there's no air resistance. Thermal energy would result from air resistance

anonymous · Answer

ohh then I'm thinking option a?

anonymous · Answer

@roadjester ?

anonymous · Answer

---

roadjester · Answer

no

anonymous · Answer

@petiteme

anonymous · Answer

ok well my last best guess is b

anonymous · Answer

@roadjester

anonymous · Answer

@petiteme

roadjester · Answer

ok look 
potential energy (U) is mgy like i said and Kinetic(K) is 1/2 mV^2
so while there is no velocity, there is no kinetic energy
while there is no height, there is no potential energy

petiteme · Answer

Someone is already helping you...

anonymous · Answer

so the answer is d!

roadjester · Answer

:(

anonymous · Answer

c??

roadjester · Answer

yes

anonymous · Answer

Last question before I go to sleep.  A 1,400 kg car is moving at 12 m/s when the driver stops the car. What increase in the thermal energy of the car and its surroundings results from applying the brakes to bring the car to a stop? Ignore other sources of thermal energy.

anonymous · Answer

my options are        2.0 × 105 J

       1.0 × 105 J

       1.7 × 104 J

       8.4 × 103 J

roadjester · Answer

@petiteme wouldn't that assume there's air resistance?

petiteme · Answer

Yes.

roadjester · Answer

@QueenBee232 are you taking Thermodynamics?

anonymous · Answer

lol basic physics

anonymous · Answer

that's how hard my school is

anonymous · Answer

in 11th

roadjester · Answer

there is no thermal energy, only kinetic

unknownrandom · Answer

It would be B if you can convert kinetic to thermal. KE=.5(m)(v)^2
KE=.5(1400kg)(12m/s)^2=1.0x10^5 J

anonymous · Answer

cool thanks! have a good night!

unknownrandom · Answer

You too! @QueenBee232

anonymous · Answer

@QueenBee232 what was the answer for the first question? C or d? please let me know.

petiteme · Answer

Why are you asking? :D

anonymous · Answer

@petiteme  because I want to know also.

petiteme · Answer

Oh okies :) Just scroll up and you'll get the answer :D