Question

A 77.4 g ball of blue putty is travelling East (to the right) with a velocity of 2.66 m/s. A second ball of red putty (54.2 g) is travelling North of West at 39 degrees with a velocity of 4.8 m/s. The two balls of putty collide and form 1 single blue/red putty blob.

The new combined blob hits a wall perpendicular to the direction of travel and sticks to it with a collision lasting 0.0031 seconds.

What magnitude force did the wall exert on the blob to stop it?

Answer 1

here,

mass of blue putty ,m1 = 0.0774 kg

mass of red Putty , m2 = 0.0542 kg

initial speed of blue putty , u1 = 2.66 m/s

initial speed of red putty , u2 = 4.8 m/s

let the final speed after the combination be v

using conservation of momentum

m1 * u1 + m2 * u2 = (m1 + m2) * v

0.0774 * 2.66 i + 0.0542 * 4.8 * ( - cos(39) i + sin(39) j) = ( 0.0774 + 0.0542) * v

solving for v

v = 0.03 m/s i + 1.25 m/s

time taken , t = 0.0031 s

the magnitude of net force , F = impulse /time taken

F = m * sqrt(0.03^2 + 1.25^2)/0.0031 N

F = (0.0774 + 0.0542) * sqrt(0.03^2 + 1.25^2)/0.0031 N

F = 66.4 N