You are sitting in a sled,at rest on a pond covered with nice, thick, frictionle

Question

You are sitting in a sled,at rest on a pond covered with nice, thick, frictionless ice. Your own mass of is 68 kg, and the mass of the sled when empty is 17.5 kg.

a) from shore, someone throws a baseball of mass 0.15 kg to you, and you catch it; the horizontal component of the ball's velocity is 22.1 m/s. What will be the sled's (and your) speed with respect to the surface of the pond after you catch the ball? Note that your answer should be in centimeters per second. (Answer cm/s)

b) Different situation: Suppose you are in the sled,and its already moving to the west, at a speed of 1.4 cm/s. From the southern shore, your friend again throws a baseball of mass 0.15 kg, which you can catch as its traveling northward with a horizontal velocity component of 26.1 m/s. In this case, what will be the sled's (and your) speed after catching the ball? (Answer cm/s)

c) Once again, suppose you start at rest on the sled out on the pond. Suddenly, you jump off of the sled, after which the empty sled is traveling at a speed of 4.8 m/s. (Note this will be the same as the horizontal component of your velocity just as you jump) (Answer in m/s)

d) That empty sled is still moving now at 4.8 m/s. A parachutist of mass 83 kg suddenely drifts straight vertically down from a helicopter, landing on the sled. What will be the sled's speed (including the parachutist) after he lands? (Answer in m/s)

Explanation / Answer

a) Linear momentum of the (ball + sled + you) is conserved in the horizontal direction since no external force is involved.

(0.15 * 22.1) = (0.15 + 17.5 + 68)v

=> v = 3.87 cm/s

b) Linear momentum of the (ball + sled + you) is conserved in the north-south direction since no external force is involved.

(0.15 * 26.1) = (0.15 + 17.5 + 68)vN

=> vN = 4.57 cm/s

So, total speed = (1.42 + 4.572)1/2 = 4.78 cm/s

c) Linear momentum is conserved.

(17.5 * 4.8) = 68v

=> v = 1.24 m/s

d) The sled's speed will not change since final momentum of the parachutist and the sled is zero in the vertical direction.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.