Physics problem.

• Nov 18th 2010, 04:19 AM
r-soy
Physics problem.
1 ) A vacum cleaner is pulled with a force of 40 N making an angle of 25 with the floor . If it is dispaced along the floor through 3 m , calculate the work done on i .

2 ) A car of mass 1500 kg being towed has a net foward force of 4500 N applied to i . The car starts from rest and travels down a horizontal highway . Find the speed of the car after it has travelled 200 m .

1)

w = FocQ Dx

=40cos25

=108.7 J

2 )

pe = pe = w = 1/2mv^2

1/2mv^2 = fcos180 200

v^2 = -1200

v = 34.6

speed =

34. 4
• Nov 18th 2010, 05:38 AM
Sudharaka
Quote:

Originally Posted by r-soy
1 ) A vacum cleaner is pulled with a force of 40 N making an angle of 25 with the floor . If it is dispaced along the floor through 3 m , calculate the work done on i .

2 ) A car of mass 1500 kg being towed has a net foward force of 4500 N applied to i . The car starts from rest and travels down a horizontal highway . Find the speed of the car after it has travelled 200 m .

1)

w = FocQ Dx

=40cos25
=108.7 J

2 )

pe = pe = w = 1/2mv^2

1/2mv^2 = fcos180 200

v^2 = -1200

v = 34.6

speed =

34. 4

Dear r-soy,

The answer of the first one is correct, although the highlighted step is incorrect (probably a typo). It should be $3\times40\times\cos25^o$

The second problem was done in an incorrect manner. Please check the highlighted part. If I give you a hint, the car is travelling to the direction of the applied force; not in the opposite direction.
• Nov 18th 2010, 08:49 AM
Unknown008
The fact that you got

v^2 = -1200

r-soy, you should have guessed that something was wrong.

And the last answer is not 34.4 m/s, but 34.6 m/s, I'll assume that you did a typo...
• Nov 18th 2010, 11:42 PM
r-soy