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# Mechanics Resolving forces watch

1. 1 ->A Toy of mass 2kg is pushed along a rough horizontal board by a horizontal force against a friction force of 5N at a constant speed of 1 m/s. Find the pushing force and the contact force between the toy and the board.

2 ->The board is not inclined at an ange of 20 to the horizontal and the pushing force remains parallel to the board. Find the new pushing force and the normal contact force between the toy and teh board.

3 ->The pushing force is now changed to act horizontally. Find the new pushing force and the normal contact force between the you and the board.

4 ->The pushing force is now increased to 15N. Find the acceleration of the toy.

Q 1->
Pushing force: 5N
Contact Force: 196N
?
2. For 2, do I use, 5cos20 ?
3. Can you post your working? I cannot help you out if I don't know what you have done.
4. Sure:

For Q1:

Pushing Force R(->), F=ma, a =0

R - 5 = 0
R = 5N

Contact Force, R (up), F=ma, a = 0

R - 2g = 0
R = 2g
R = 19.6N

For question 2:

R(->) = -5 + 2gsin20 (is this correct?)
R = 16.97N

Contact Force, R (up), F=ma, a = 0

R - 19.6sin(70)
R = 18.41N

Question 3 is where I'm stuck....
5. For Q3, Would R(->) = 5sin(20) ?

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Updated: January 19, 2010
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