Concept #1: Push-Away Problems

Practice: An 80-kg astronaut is floating in space is 30 m away from his spaceship. He wants to return to his spaceship in 10 s. With how much speed must he throw his 2-kg space hammer, directly away from the spaceship, to accomplish this?

Example #1: More Push-Away Problems

Example #2: More Push-Away Problems

Example #3: Walking on a Canoe

Margie (of mass 41 kg) and Bill (of mass 65 kg), both with brand new roller blades, are at rest facing each other in the parking lot. They push off each other and move in opposite directions, with Margie moving at a constant speed of 18 ft/s. At what speed is Bill moving?
1. 12.5735
2. 8.4
3. 9.0
4. 13.871
5. 7.61905
6. 8.65574
7. 11.9118
8. 11.3538
9. 10.2857
10. 9.53333

A(n) 56.8 kg astronaut becomes separated from the shuttle, while on a space walk. She finds herself 54.2 m away from the shuttle and moving with zero speed relative to the shuttle. She has a(n) 0.676 kg camera in her hand and decides to get back to the shuttle by throwing the camera at a speed of 12 m/s in the direction away from the shuttle.How long will it take for her to reach the shuttle?A. 8.223 minB. 7.590 minC. 8.539 minD. 7.274 minE. 6.958 minF. 7.906 minG. 6.325 min H. 9.171 min

A 66.5 kg astronaut is doing a repair in space on the orbiting space station. She throws a 2.40 kg tool away from her at 3.40 m/s relative to the space station.(a) With what speed will she begin to move?(b) In what direction will she begin to move?

Adam ( mA = 80 Kg) and Barbara (mB = 60 Kg) are initially together at rest on an ice rink. When they push each other part, Adam moves with velocity vA = (3 m/s)î - (9 m/s)jˆ. Assuming that there is no friction from the ice, what is Adam’s velocity?
[a] (-4 m/s)î + (12 m/s)jˆ
[b] (4 m/s)î - (12 m/s)jˆ
[c] (-9/4 m/s)î + (24/7 m/s)jˆ
[d] (3 m/s)î - (9 m/s)jˆ
[e] (4 m/s)î + (12 m/s)jˆ

Squids and octopuses propel themselves by expelling water. They do this by keeping water in a cavity and then suddenly contracting the cavity to force out the water through an opening. A 7.00 kg squid (including the water in the cavity) at rest suddenly sees a dangerous predator. If the squid has 1.75 kg of water in its cavity, at what speed must it expel this water to instantaneously achieve a speed of 2.60 m/s to escape the predator? Neglect any drag effects of the surrounding water.

A firecracker in a coconut blows the coconut into three pieces. Two pieces of equal mass fly off south and west, perpendicular to each other, at 20 m/s. The third piece has twice the mass as the other two.(a) What is the speed of the third piece?(b) What is the direction of the third piece? Give the direction as an angle east of north.

A 800 kg cart is rolling to the right at 3.30 m/s. A 80.0 kg man is standing on the right end of the cart. What is the speed of the cart if the man suddenly starts running to the left with a speed of 9.00 m/s relative to the cart?

A child in a boat throws a 5.05-kg package out horizontally with a speed of 10.0 m/s. Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the child is 26.0 kg and that of the boat is 45.0 kg. (Take the packages direction of motion as positive.)

A(n) 17 kg object, initially at rest in free space, “explodes” into three segments. The masses of two of these segments are both 6 kg and their velocities are 3.3 m/s. The angle between the direction of motion of these segments is 97°. What is the speed of the third segment?
1. 5.8619
2. 7.75265
3. 7.32878
4. 5.24795
5. 7.41844
6. 4.92044
7. 5.70456
8. 7.18373
9. 15.8468
10. 5.17423

A man whose mass is 85 kg and a woman whose mass is 50 kg sit at opposite ends of a canoe 5 m long, whose mass is 45 kg. Assume the man is seated at x = 0 and the boat extends along the positive x axis with the woman at the other end. Suppose that the man moves quickly to the center of the canoe and sits down there, while the woman moves quickly 1/3 the length of the canoe towards the man. How far does the canoe move in the water? Assume force of friction between water and the canoe is negligible.
1. 0.972222
2. 0.864865
3. 0.72
4. 1.18056
5. 0.903226
6. 3.29
7. 1.59375
8. 1.13636
9. 0.944444
10. 1.35484