A group of students is making model cars that will be propelled by model rocket engines. These engines provide a nearly constant thrust force. The cars are light—most of the weight comes from the rocket engine—and friction and drag are very small. As the engine fires, it uses fuel, so it is much lighter at the end of the run than at the start. A student ignites the engine in a car, and the car accelerates. As the fuel burns and the car continues to speed up, the magnitude of the acceleration will
A. Increase.
B. Stay the same.
C. Decrease.
Want to see the full answer?
Check out a sample textbook solutionChapter 4 Solutions
College Physics: A Strategic Approach (3rd Edition)
Additional Science Textbook Solutions
Cosmic Perspective Fundamentals
Microbiology: An Introduction
Campbell Essential Biology (7th Edition)
Human Biology: Concepts and Current Issues (8th Edition)
Fundamentals of Anatomy & Physiology (11th Edition)
Campbell Essential Biology with Physiology (5th Edition)
- There is a compressed spring between two laboratory carts of masses m1 = 105 g and m2 = 212 g. Initially, the carts are held at rest on a horizontal track (Fig. P10.40A). The carts are released, and the cart of mass m1 has velocity vi=2.035i m/s in the positive x direction (Fig. 10.40B). Assume rolling friction is negligible. a. What is the net external force on the two-cart system? b. Find the velocity of cart 2. FIGURE P10.40 Problems 40 and 41.arrow_forwardTwo figure skaters are coasting in the same direction, with the leading skater moving at 5.5 m/s and the trailing skating moving at 6.2 m/s. When the trailing skater catches up with the leading skater, he picks her up without applying any horizontal forces on his skates. If the trailing skater is 50 heavier than the 50-kg leading skater, what is their speed after he picks her up?arrow_forwardA 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.arrow_forward
- A cart filled with sand rolls at a speed of 1.0 m/s along a horizontal path without friction. A ball of mass m = 2.0 kg is thrown with a horizontal velocity of 8.0 m/s toward the cart as shown in Figure P11.79. The ball gets stuck in the sand. What is the velocity of the cart after the ball strikes it? The mass of the cart is 15 kg. FIGURE P11.79 Problems 79 and 80.arrow_forwardIn a head-on, inelastic collision, a 4,000-kg truck going 10 m/s east strikes a 1,000-kg car going 20 m/s west. (a) What is the speed and direction of the wreckage? (b) How much kinetic energy was lost in the Collision?arrow_forwardHow much fuel would be needed for a 1000-kg rocket (this is its mass with no fuel) to take off from Earth and reach 1000 m/s in 30 s? The exhaust speed is 1000 m/s.arrow_forward
- The cryogenic main stage of a rocket has an exhaust speed of 4.21 103 m/s and burns liquid hydrogen and liquid oxygen at a combined rate of 317 kg/s. a. What is the thrust produced by the rockets main engine? b. If the initial mass of the rocket is 1.10 105 kg, what is the initial acceleration of the rocket upon liftoff from the Earth?arrow_forwardA Boeing 737—a small, short-range jet with a mass of 51,000 kg— sits at rest at the start of a runway. The pilot turns the pair of jet engines to full throttle, and the thrust accelerates the plane down the runway. After traveling 940 m, the plane reaches its takeoff speed of 70 m/s and leaves the ground. What is the thrust of each engine?arrow_forwardA 2.5 kg ball strikes a wall with the velocity of 8.5 m/s to the left the ball bounces off with a velocity of 7.5 m/s to the right. if the ball is in contact with the wall for 0.2s, what is the force exerted on the ball by the wall.arrow_forward
- A cat of 20 kg mass is running at 8.0 m/s toward a stationary skateboard with a mass of 2 kg. The cat jumps on the skateboard once it reaches it. The skateboard and cat roll forward together without friction until they reach a ramp 30◦ above horizontal. If the coefficient of kinetic friction between the skateboard and the ramp is µk =0.3, what is the maximum height the skateboard can reach?arrow_forwardA machine gun fires 150 g bullets at a speed of 1000 m/s. The gunman holding the machine gun in his hands can exert an average force of 200 N against the gun. Find the maximum number of bullets that can be fired per minute. 70 60 90 80arrow_forwardDr. Knotts is playing in a Bags tournament. Every time he makes a toss, the bag slides off the back of theboard. He focuses very hard on his next toss to try to keep it on the board. His bag hits the board with aninitial velocity (parallel to the board) of 2.8??. The coefficient of kinetic friction between the bag and theboard is 0.12 and the mass of the bag is 0.45 ??. The board is at an incline of 15° above the horizontal.a. Draw a free-body diagram for the bag on the board. Mark the direction of motion and thedirection of acceleration next to your free-body diagram.b. What is the magnitude of the normal force on the bag?c. What is the magnitude of the kinetic friction force on the bag?d. What is the net acceleration of the bag? (magnitude and direction)4e. The bag lands on the board with 0.85 ? of board remaining. Does the bag stay on the board ordoes it slide off of the back again? You will use a kinematics equation to solve this.arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningClassical Dynamics of Particles and SystemsPhysicsISBN:9780534408961Author:Stephen T. Thornton, Jerry B. MarionPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Physics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningUniversity Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice University