Exam 7: Impulse and Momentum

A 4.0-kg block slides along a frictionless surface with a constant speed of 5.0 m/s as shown.Two seconds after it begins sliding, a horizontal, time-dependent force is applied to the mass.The force is removed eight seconds later.The graph shows how the force on the block varies with time. -What, approximately, is the speed of the block at t = 11 seconds?

A 100-kg cannon at rest contains a 10-kg cannon ball.When fired, the cannon ball leaves the cannon with a speed of 90 m/s.What is the recoil speed of the cannon?

A stunt person jumps from the roof of a tall building, but no injury occurs because the person lands on a large, air-filled bag.Which one of the following best describes why no injury occurs?

During hockey practice, two pucks are sliding across the ice in the same direction.At one instant, a 0.18-kg puck is moving at 16 m/s while the other puck has a mass of 0.14 kg and a speed of 3.8 m/s.What is the velocity of the center of mass of the two pucks?

A 50.0-kg boy runs at a speed of 10.0 m/s and jumps onto a cart as shown in the figure.The cart is initially at rest.If the speed of the cart with the boy on it is 2.50 m/s, what is the mass of the cart?

A 0.10-kg cart traveling in the positive x direction at 10.0 m/s collides with a 0.30-kg cart at rest.The collision is elastic.What is the velocity of the 0.10-kg cart after the collision?

A sled of mass m is coasting on the icy surface of a frozen river.While it is passing under a bridge, a package of equal mass m is dropped straight down and lands on the sled (without causing any damage).The sled plus the added load then continue along the original line of motion.How does the kinetic energy of the (sled + load) compare with the original kinetic energy of the sled?

In which one of the following situations is linear momentum not conserved?

A rocket is launched vertically from rest; and it burns fuel at a constant rate of 136 kg/s.Exhaust gases are expelled with a speed of 5.25 × 10³ m/s relative to the rocket.What is the magnitude of the thrust?

A stationary 4-kg shell explodes into three pieces.Two of the fragments have a mass of 1 kg each and move along the paths shown with a speed of 10 m/s.The third fragment moves upward as shown. -What is the speed of the center of mass of this system after the explosion?

An airplane is traveling at 225 m/s when it strikes a weather balloon (m = 1.82 kg), which can be considered to be at rest relative to the ground below.After the collision, the balloon is caught on the fuselage and is traveling with the airplane.The collision takes place over a time interval of 4.44 × 10^-3 N.What is the average force that the balloon exerts on the airplane during the collision?

Two objects constitute an isolated system.In an elastic collision between the two objects, which one of the following statements is a false statement?

While in Earth's orbit, an 80-kg astronaut carrying a 20-kg tool kit is initially drifting toward a stationary (relative to her) space shuttle at a speed of 2 m/s.If she throws the tool kit toward the shuttle with a speed of 6 m/s as seen from the shuttle, her final speed is

A space vehicle of mass m has a speed v.At some instant, it separates into two pieces, each of mass 0.5m.One of the pieces is at rest just after the separation. -Which one of the following statements concerning this situation is true?

A 2.0-kg pistol fires a 1.0-g bullet with a muzzle speed of 1000 m/s.The bullet then strikes a 10-kg wooden block resting on a horizontal frictionless surface.The block and the embedded bullet then slide across the surface. -The explosive charge in the pistol acts for 0.001 s.What is the average force exerted on the bullet while it is being fired?

Complete the following statement: A collision is elastic if

A tennis ball has a velocity of 12 m/s downward just before it strikes the ground and bounces up with a velocity of 12 m/s upward.Which statement is true concerning this situation?

A bat strikes a 0.050-kg baseball so that its velocity changes by +32 m/s in 0.080 s.With what average force was the ball struck?

A comet fragment of mass 1.96 × 10¹³ kg is moving at 6.50 × 10⁴ m/s when it crashes into Callisto, a moon of Jupiter.The mass of Callisto is 1.08 × 10²³ kg.The collision is completely inelastic. -Car One is traveling due north and Car Two is traveling due east.After the collision shown, Car One rebounds in the due south direction.Which of the numbered arrows is the only one that can represent the final direction of Car Two?

A juggler demonstrates his abilities by keeping a 2.3-kg pipe wrench, a 1.5-kg hatchet, and a 1.0-kg hammer flying through the air above his head.The white circles on the graph represent the positions of the center of mass of each of the flying objects at one instant.What are the x and y coordinates of the center of mass for the system of these three objects? x y