A knife thrower throws a knife toward a 300 g target that is sliding in her direction at a speed of 2.05 m/s on a horizontal frictionless surface. She throws a 22.5 g knife at the target with a speed of 36.0 m/s. The target is stopped by the impact and the knife passes through the target. Determine the speed of the knife (in m/s) after passing through the target. m/s

A knife thrower throws a knife toward a 300 g target that is sliding in her direction at a speed of 2.05 m/s on a horizontal frictionless surface. She throws a 22.5 g knife at the target with a speed of 36.0 m/s. The target is stopped by the impact and the knife passes through the target. Determine the speed of the knife (in m/s) after passing through the target. m/s

Physics for Scientists and Engineers

10th Edition

ISBN:9781337553278

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter9: Linear Momentum And Collisions

Section: Chapter Questions

Problem 45AP: Review. A bullet of mass m = 8.00 g is fired into a block of mass M = 250 g that is initially at...

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Review. A 60.0-kg person running at an initial speed of 4.00 m/s jumps onto a 120-kg cart initially at rest (Fig. P9.37). The person slides on the carts top surface and finally comes to rest relative to the cart. The coefficient of kinetic friction between the person and the cart is 0.400. Friction between the cart and ground can be ignored. (a) Find the final velocity of the person and cart relative to the ground. (b) Find the friction force acting on the person while he is sliding across the top surface of the cart. (c) How long does the friction force act on the person? (d) Find the change in momentum of the person and the change in momentum of the cart. (c) Determine the displacement of the person relative to the ground while he is sliding on the cart. (f) Determine the displacement of the cart relative to the ground while the person is sliding. (g) Find the change in kinetic energy of the person. (h) Find the change in kinetic energy of the cart. (i) Explain why the answers to (g) and (h) differ. (What kind of collision is this one, and what accounts for the loss of mechanical energy) Figure P9.37
A 100-g firecracker is launched vertically into the air and explodes into two pieces at the peak of its trajectory. If a 72-g piece is projected horizontally to the left at 20 m/s, what is the speed and direction of the other piece?
A 0.240-kg billiard ball that is moving at 3.00 m/s strikes the bumper of a pool table and bounces straight back at 2.40 m/s (80% of its original speed). The collision lasts 0.0150 s. (a) Calculate the average force exerted on the ball by the bumper. (b) How much kinetic energy in joules is lost during the collision? (c) What percent of the original energy is left?
A 0.500-kg sphere moving with a velocity expressed as (2.00i3.00j+1.00k)m/s strikes a second, lighter sphere of mass 1.50 kg moving with an initial velocity of (1.00i+2.00j3.00k)m/s. (a) The velocity of the 0.500-kg sphere after the collision is (1.00i+3.00j8.00k)m/s. Find the final velocity of the 1.50-kg sphere and identify the kind of collision (elastic, inelastic, or perfectly inelastic). (b) Now assume the velocity of the 0.500-kg sphere after the collision is (0.250i+0.750j2.00k)m/s. Find the final velocity of the 1.50-kg sphere and identify the kind of collision. (c) What If? Take the velocity of the 0.500-kg sphere after the collision as (1.00i+3.00jak)m/s. Find the value of a and the velocity of the 1.50-kg sphere after an elastic collision.
A block with mass m1 = 0.500 kg is released from rest on a frictionless track at a distance h1, = 2.50 m above the top of a table. It then collides elastically with an object having mass m2 = 1.00 kg that is initially at rest on the table, as shown in Figure P6.71. (a) Determine the velocities of the two objects just after the collision. (b) How high up the track does the 0.500-kg object travel back after the collision? (c) How far away from the bottom of the table does the1.00-kg object land, given that the height of the table h2 = 2.00 m? (d) How far away from the bottom of the table does the 0.500-kg object eventually band? Figure P6.71
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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 space-walk? Assume the fuel burns at a constant rate.
Problems 44 and 45 are paired. C A model rocket is shot straight up. As it reaches the highest point in its trajectory, it explodes in midair into three pieces with velocities indicated by the arrows in Figure P10.44, as viewed from directly above the explosion. Rank the mass of each piece in order from smallest to largest and justify your answer. FIGURE P10.44 Problems 44 and 45.
A car crashes into a large tree that does not move. The car goes from 30 m/s to 0 in 1.3 m. (a) What impulse is applied to the driver by the seatbelt, assuming he follows the same motion as the car? (b) What is the average force applied to the driver by the seatbelt?
A soccer player runs up behind a 0.450-kg soccer ball traveling at 3.20 m/s and kicks it in the same direction as it is moving, increasing its speed to 12.8 m/s. (a) What is the change in the magnitude of the balls momentum? (b) What magnitude impulse did the soccer player deliver to the ball? (c) What magnitude impulse would be required to kick the ball in the opposite direction at 12.8 m/s, instead? (See Section 6.1.)
A 44.0-kg child finds himself trapped on the surface of a frozen lake, 10.0 m from the shore. The child slips with each step on the frictionless ice and remains the same distance from the shoreline. Egged on by his parents, he throws a 0.750-kg ball he is carrying toward the center of the lake with a horizontal speed of 1.50 m/s, in the direction opposite that of the shoreline. a. Does the act of throwing the ball cause the child to move? If so, what are the speed and the direction of his motion with respect to the Earth? b. What are the forces acting on the child when he throws the ball?
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