Is there an error in the answer for Impulse Momentum Linear Homework?

[Doc Al]

I got confused with this question part a (i). I know how to solve this question, I tried to used the same method and got the answer. But when I tried it on the previous hammer question with the working of:

M1=mv
=(9000)(8.82)
=79380

M2=mv
=0

I1-2=Force x Time
=(F)(0.1)
=0.1F

M1+I1-2=M2

79380-0.1F=0
79380=0.1F
F=793800 Ans Wrong

Because you said this is the net force and plus the rest of the explanation totally make me lost in space This 3 marks is so damn hard

Once again: F is the net force, but they ask for the resistive force. So use the net force to solve for the resistive force. (Review post #28)

 

[freshbox]

Post #35 Question 7ai working:

M₁=mv
=1000x19.44
=19444.44

M₂=mv
=1000x16.67
=16666.67

T_1-2= F x T
=-Fx4
=-4F

M₁+I_1-2=M₂
19444.44-4F=16666.67
-4F=-2777.77
F=694.4N Answer

So this 694.4N is the net force, and there is another resistive force?

I tried to apply this style of working on the hammer question, but you told me that is the net force and ask me to find the other resistive force

I got confused here with this part and the hammer question, I hope you know what i meant...

 

[Doc Al]

Post #35 Question 7ai working:

M₁=mv
=1000x19.44
=19444.44

M₂=mv
=1000x16.67
=16666.67

T_1-2= F x T
=-Fx4
=-4F

M₁+I_1-2=M₂
19444.44-4F=16666.67
-4F=-2777.77
F=694.4N Answer

So this 694.4N is the net force, and there is another resistive force?

In this case, the net force is the 'net resistive force', so that's your answer.

I tried to apply this style of working on the hammer question, but you told me that is the net force and ask me to find the other resistive force

I got confused here with this part and the hammer question, I hope you know what i meant...

In the hammer question you had two individual forces acting: gravity and the resistive force of the ground.

In the car question they just want the net resistive force (gravity doesn't enter into it, since he's on level ground).

 

[freshbox]

Ok can, understood. Thanks for the explanation again at least I have a clearer picture now, Sorry for being too slow Tomorrow is my finals, wish me all the best!