11. Momentum & Impulse

An 80-kg astronaut is stranded floating in space is 30 m away from his spaceship. He wants to return to his spaceship in 20 s. How fast must he throw his 2-kg space hammer, directly away from the spaceship, to accomplish this?

(II) A 0.145-kg baseball pitched horizontally at 35.0 m/s strikes a bat and pops straight up to a height of 31.5 m. If the contact time between bat and ball is 2.5 ms, calculate the average force between the ball and bat during contact.

(II) The force on a bullet along the barrel of a firearm is given by the formula F = [740 ― (2.3 x 10⁵ s⁻¹ ) t] N over the time interval t = 0 to t = 3.0 x 10⁻³ s .

(e) What is the recoil speed of the 4.5-kg gun?

(III) A 360-kg four-wheel flat cart 15 m long is moving horizontally with a speed of 6.0 m/s. A 110-kg worker starts walking from one end of the cart to the other in the direction of motion, with speed 2.0 m/s with respect to the cart. In the time it takes for him to reach the other end, how far has the cart moved?

An astronaut of mass 210 kg including his suit and jet pack wants to acquire a velocity of 2.0 m/s to move back toward his space shuttle. Assuming the jet pack can eject gas with a velocity of 35 m/s, what mass of gas will need to be ejected?

(II) A child in a boat throws a 5.30-kg package out horizontally with a speed of 10.0 m/s, Fig. 9–39. Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the child is 24.0 kg and that of the boat is 42.0 kg.

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BIO Squids rely on jet propulsion to move around. A 1.50 kg squid (including the mass of water inside the squid) drifting at 0.40 m/s suddenly ejects 0.100 kg of water to get itself moving at 2.50 m/s . If drag is ignored over the small interval of time needed to expel the water (the impulse approximation), what is the water’s ejection speed relative to the squid?