December 1, 2015

Homework Help: Physics

Posted by Audrey on Wednesday, November 7, 2012 at 4:47pm.

A rubber ball (mass 0.30 kg) is dropped from a height of 2.0 m onto the floor. Just after bouncing from the floor, the ball has a speed of 3.9 m/s.

(a) What is the magnitude and direction of the impulse imparted by the floor to the ball?

MAGNITUDE: 3.05 kg m/s
V1 (velocity before) = the square root of 2gh,
v1=square root 2 times gravity(9.8) times the height given, in this case, 2.0m.

v1= sq root (2)(9.8m/s)(2m) =6.260990337

NEXT: use the ans you just got, and plug it in to this equation, which would give you the magnitude.

The ans for v1, or the velocity before the collision, multiplied by the mass, added to the velocity after the collision which is mulitipled by the mass.

(6.2609m/s)*(.30kg)+(3.9 m/s)*(.30 kg)

if you do it sets, v1*m, (6.2609 m/s)*(.30kg) =1.878....

v2*m (3.9 m/s) * (.30 kg) = 1.17 kg m/s

finally, put the two sets together, if you did it seperatly,
1.878 + 1.17= 3.048 kg m/s

rounded, 3.05 for P


(b) If the average force of the floor on the ball is 16 N, how long is the ball in contact with the floor?


- = N

divide p on both sides, to solve for T, time, using simple algebra.

1 N
- = -

Next, subsitute the value of the variable, STVOTV.

You want to fill in what we know, we know N= 16, and P=3.05, (what we just solved for), and we know the number 1 is there.

With the info we have,

1 16
- = -
T 3.05

16 divided by 3.05=
16/3.05 = 5.245....

LAST STEP, notice


divide 1 by your answer, (5.245...)=
1 / 5.245 = .190625 s

answer is .190625 s
rounded, .01906

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