Exam 7: Rotational Motion and the Law of Gravity: Part A

A 20-g bullet moving at 1000 m/s is fired through a one-kg block of wood emerging at a speed of 200 m/s.What is the change in the kinetic energy of the bullet-block system as a result of the collision assuming the block is free to move?

Three masses are moving along the x-axis.Their masses and velocities are ​m​₁ = ​m​ with ​v_​1 = ​v​,​m_​2 = 2​m with v₂ = 2v,and m₃ = 3m with v₃ = -3v ​(the minus sign indicating this velocity is in the negative x-direction).The three masses collide and stick together in a completely inelastic collision.What is the resultant velocity of the combined mass?

Ann the Astronaut weighs 60 kg.She is space-walking outside the space shuttle and pushes a 270-kg satellite away from the shuttle at 0.90 m/s.What speed does this give Ann as she moves toward the shuttle?

A machine gun is attached to a railroad flatcar that rolls with negligible friction.If the railroad car has a mass of 6.25 × 10⁴ kg,how many bullets of mass 25 g would have to be fired at 250 m/s off the back to give the railroad car a forward velocity of 0.3 m/s?

A car wash nozzle directs a steady stream of water at 1.5 kg/s,with a speed of 20 m/s,against a car window.What force does the water exert on the glass? Assume the water does not splash back.

A 1000-kg vehicle is moving in the positive y-direction along the y-axis at 10 m/s.A 2000-kg vehicle is moving in the positive x-direction at along the x-axis at 20 m/s.The vehicles collide and stick together.They move as a single object in a direction ​θ as measured counterclockwise from the x-axis immediately after the collision.What is the value of tan ​θ?

Mitch throws a 100-g lump of clay at a 200-g target,which is at rest on a horizontal surface.After impact,the target,including the attached clay,slides 2.1 m before stopping.If the coefficient of friction is µ = 0.50,find the speed of the clay before impact.

A 6-kg object is moving to the right at 4 m/s and collides with a 4-kg object moving to the left at 6 m/s.The objects collide and stick together.After the collision,the combined object:

A rock is moving with speed v.If the mass of the rock were tripled and the speed were reduced to v/3,which of the following statements would be true?

A model car is propelled by a cylinder of carbon dioxide gas.The cylinder emits gas at a rate of 4.5 g/s with an exit speed of 80.0 m/s.The car has a mass of 200 g,including the CO₂ cylinder.Starting from rest,what is the car's initial acceleration?

A system of 3 masses is located as follows: m₁ = m₀ at (0,L),m₂ = 2m₀ at the origin,and m₃ = 3m₀ at (3L,0).Where is the center of mass of these masses?

A billiard ball is moving in the x direction at 40.0 cm/s and strikes another billiard ball moving in the y direction at 30.0 cm/s.As a result of the collision,the first ball moves at 50.0 cm/s,and the second ball stops.What is the change in kinetic energy of the system as a result of the collision?

Alex throws a 0.43-kg rubber ball down onto the floor.The ball's speed just before impact is 6.5 m/s,and just after is 5.5 m/s.What is the magnitude of the change in the ball's momentum?

A helicopter stays aloft by pushing large quantities of air downward every second.What mass of air must be pushed downward at 30.0 m/s every second to keep a 1000 kg helicopter aloft?

An unfueled 1 000-kg experimental rocket sled on level frictionless rails is loaded with 50 kg of propellant.It exhausts the propellant in a 20 s "burn." If the rocket,initially at rest,moves at 160 m/s after the burn,what impulse is experienced by the rocket sled?

A 20-g bullet moving at 1000 m/s is fired through a one-kg block of wood emerging at a speed of 200 m/s.What is the kinetic energy of the block that results from the collision if the block had not been moving prior to the collision and was free to move?

An unfueled 1000-kg experimental rocket sled at rest on level frictionless rails is loaded with 50 kg of propellant.It exhausts the propellant in a 20 s "burn." The rocket moves at 160 m/s after the burn.What average force is experienced by the rocket during the burn?

A 0.12-kg ball is moving at 6.0 m/s when it is hit by a bat,causing it to reverse direction and have a speed of 8.0 m/s.What is the magnitude of the change in the momentum of the ball?

A "double satellite" is launched into space.It consists of a satellite of mass m and another satellite of mass 5m.The connecting mechanism of these satellites is an explosive bolt and a compressed spring,both of negligible mass.The bolt is exploded and the satellites drift apart having been pushed by the spring.When the less massive satellite has moved a distance of 2.5 m from the center of mass of the double satellite,how far away from it is the satellite of greater mass?

At liftoff,the engines of the Saturn V rocket consumed 14,000 kg/s of fuel and exhausted the combustion products at 2900 m/s.What was the total upward force (thrust)provided by the engines?