Revised seed 111

course PHY 121

•How much net force is required to accelerate a 12 kg mass at 3 m/s^2? 12*3=36

###I got this right but did not include units. It would be 12kg * 3m/s^2=36kgm/s^2=36Newtons(F=ma)

answer/question/discussion:

• What would be the acceleration of a 4 kg mass subject to a net force of 20 Newtons?

4*20=80

###This should be 20N / 4kg=20kgm/s^2/4kg=5m/s^2

answer/question/discussion:

• If you exert a force of 20 Newtons on a 10-kg object and it accelerates in the direction of your force at 1.5 m/s^2, then how do you know there are other forces acting on the object besides your own?

20/10=2

###10kg*1.5m/s^2=15kg m/s^2=15N

Because you need more force to move at 1.5m/s^2

You don't 'move at' 1.5 m/s^2. You accelerate at 1.5 m/s^2. This is the rate at which the velocity changes.

You can be moving forward or backward, fast or slow, while accelerating at 1.5 m/s^2.

answer/question/discussion:

• What is the total of all those forces and in what direction does this total act?

36+80+2= 118

###This should be 20Newtons-15Newtons=5N

&#Good work. See my notes and let me know if you have questions. &#