A1.2-kg object moving with a speed of 8.0 m/s collidesperpendicularly with a wall and emerges with a speed of 6.0 m/s inthe opposite direction. if the object is in contact with the wallfor 2.0 ms, what is the magnitude of the average force on theobject by the wall?
a. 9.8 knb. 8.4 knc. 7.7 knd. 9.1 kne. 1.2 kn

The appropriate answer is Option b (8.4 kN).

Given values are:

Mass of the object,

m = 1.2 kg

Initial speed,

u = 8 m/s

Final speed,

v = -6 m/s

Time,

t = 2 ms

or,

 =

Now,

→ The Force is:

By substituting the values, we get

or,

Thus the above is the correct solution.

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that would be because of both gravity and friction. so     c

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form