Two metal balls are the same size but ball A weighs 20 N and ball B weighs 10 N. Ball B is dropped one second before ball A from the roof of a 100 m tall building to the sidewalk below. If the effects of air can be ignored, then at what point will ball A catch up to ball B.

Review. The first stage of a Saturn V space vehicle consumed fuel and oxidizer at the rate of 150 104 kg/s with an exhaust speed of 2.60 101 m/s. (a) Calculate the thrust produced by this engine. (b) Find the acceleration the vehicle had just as it lifted off the launch pad on the Earth, taking the vehicles initial mass as 3.00 106 kg.

A 57.0-g tennis ball is traveling straight at a player at 21.0 m/s. The player volleys the ball straight back at 25.0 m/s. If the ball remains in contact with the racket for 0.060 s, what average force acts on the ball? (a) 22.6 N (b) 32.5 N (c) 43.7 N (d) 72.1 N (e) 102 N

A garden hose is held as shown in Figure P9.32. The hose is originally full of motionless water. What additional force is necessary to hold the nozzle stationary after the water flow is turned on if the discharge rate is 0.600 kg/s with a speed of 25.0 m/s? Figure P9.32

A model rocket engine has an average thrust of 5.26 N. It has an initial mass of 25.5 g, which includes fuel mass of 12.7 g. The duration of its burn is 1.90 s. (a) What is the average exhaust speed of the engine? (b) This engine is placed in a rocket body of mass 53.5 g. What is the final velocity of the rocket if it were to be fired from rest in outer space by an astronaut on a spacewalk? Assume the fuel burns at a constant rate.

NASAs Saturn V rockets that launched astronauts to the moon were powered by the strongest rocket engine ever developed, providing 6.77 106 N of thrust while burning fuel at a rate of 2.63 103 kg/s. Calculate the engines exhaust speed.

A ballistic pendulum is used to measure the speed of bullets. It comprises a heavy block of wood of mass M suspended by two long cords. A bullet of mass m is fired into the block horizontally. The block, with the bullet embedded in it, swings upward (Fig. P10.70). The center of mass of the combination rises through a vertical distance h before coming to rest momentarily. In a particular experiment, a bullet of mass 40.0 g is fired into a wooden block of mass 10.0 kg. The blockbullet combination is observed to rise to a maximum height of 20.0 cm above the blocks initial height. a. What is the initial speed of the bullet? b. What is the fraction of initial kinetic energy lost after the bullet is embedded in the block? FIGURE P10.70

A rocket has total mass Mi = 360 kg, including Mfuel = 330 kg of fuel and oxidizer. In interstellar space, it starts from rest at the position x = 0, turns on its engine at time t = 0, and puts out exhaust with relative speed ve = 1 500 m/s at the constant rate k = 2.50 kg/s. The fuel will last for a burn time of Tb = Mfuel/k = 330 kg/(2.5 kg/s) = 132 s. (a) Show that during the burn the velocity of the rocket as a function of time is given by v(t)=veln(1ktMi) (b) Make a graph of the velocity of the rocket as a function of time for times running from 0 to 132 s. (c) Show that the acceleration of the rocket is a(t)=kveMikt (d) Graph the acceleration as a function of time. (c) Show that the position of the rocket is x(t)=ve(Mikt)ln(1ktMi)+vet (f) Graph the position during the burn as a function of time.

A person of mass m stands on a rope ladder that is hanging from a freely floating balloon of mass M. The balloon is initially at rest with respect to the ground. (The buoyant force on the personballoon system is countering the force of gravity.) a. In what direction will the balloon move if the person starts to climb the rope ladder at constant velocity v relative to the ladder? b. At what speed will the balloon move if the person starts to climb the rope ladder at constant velocity v relative to the ladder?

A single-stage rocket of mass 308 metric tons (not including fuel) carries a payload of 3150 kg to low-Earth orbit. The exhaust speed of the rockets cryogenic propellant is 3.20 103 m/s. a. If the speed of the rocket as it enters orbit is 8.00 km/s, what is the mass of propellant used during the rockets burn? b. The rocket is redesigned to boost its exhaust speed by a factor of two. What is the mass of propellant used in the redesigned rocket to carry the same payload to low-Earth orbit? c. Because the exhaust speed of the redesigned rocket is increased by a factor of two, why is the fuel consumption of the redesigned rocket not exactly half that of the original rocket?