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1.To get off a frozen, frictionless lake, a 68.7 -kg person takes off a 0.256 -k

ID: 1459082 • Letter: 1

Question

1.To get off a frozen, frictionless lake, a 68.7-kg person takes off a 0.256-kg shoe and thows it horizontally directly away from the shore with a speed of 1.86 m/s.

If the person is 5.44m from the shore, how long does it take for

him to reach it?

2.  A 0.267 kg volley ball comes over the net with a horizontal velocity of 3.80 m/s. One of the players on the front line jumps up and hits it back with a horizontal velocity of 11.1 m/s. What was the impulse imparted to the ball?

3.

A mass, M1 = 3 kg, slides across a frictionless table with a velocity, v1 = 8 m/s, as shown in the drawing. The mass collides with, and sticks to, a mass, M2 = 2 kg, which is initially at rest.

What is the velocity of the pair of masses after the collision?

Explanation / Answer


1, Use the kinematic equation S = ut

so

t = S/u = 5.44/1.86 = 2.924 secs

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2. use Impulse J = Force * time = Change in Momentum

J = F t = MdV

J = 0.276 *(11.1-(-3.8)

J = 4.11 Ns

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3, yse from the law of conservation of momemtum

m1u1 + m2u2 = (m1+m2) V

V = 3* 8 + (2 *0) /(3+2)

V = 4.8 m/s