Concept explainers
The 1.0 kg block in FIGURE EX7.24 is tied to the wall with a rope. It sits on top of the 2.0 kg block. The lower block is pulled to the right with a tension force of 20 N. The coefficient of kinetic friction at both the lower and upper surfaces of the 2.0 kg block is
a. What is the tension in the rope attached to the wall?
b. What is the acceleration of the 2.0 kg block?
FIGURE EX7.24
Learn your wayIncludes step-by-step video
Chapter 7 Solutions
MASTERPHYS:KNIGHT'S PHYSICS ACCESS+WKB
Additional Science Textbook Solutions
Cosmic Perspective Fundamentals
Microbiology with Diseases by Body System (5th Edition)
Biology: Life on Earth with Physiology (11th Edition)
Microbiology: An Introduction
Biology: Life on Earth (11th Edition)
Campbell Essential Biology (7th Edition)
- In short-track speed skating, the track has straight sections and semicircles 16 m in diameter. Assume that a 65 kg skater goes around the turn at a constant 12 m/s.a. What is the horizontal force on the skater?b. What is the ratio of this force to the skater’s weight?arrow_forwardI watched a lot of Looney Toons when I was a kid, and liked that the Roadrunners legs would spin for a second or two before their claws caught traction. a. With a coefficient of kinetic friction 0.2 what acceleration will the roadrunner experience while their feet are sliding accross the ground? b. How far forward will the roadrunner drift in a half second, starting from rest under this acceleration? c. After catching traction the Roadrunner accelerates away, travelling 10 m to get offscreen in one fifth of a second. What was their coefficient of static friction?arrow_forwardTwo blocks are connected via a massless frictionless pully system. The hanging block is 3 kg. The other block is on a ramp of 25◦ and has a mass m. The coefficients of friction between the block on the ramp and the ramp are: µs = .8 and µk = .5. a. What is the minimum mass m that will not slip? b. If the minimum mass is nudged, it will start being pulled up the incline. What will the acceleration be when that happens?arrow_forward
- Your forehead can withstand a force of about 6.0 kN before fracturing, while your cheekbone can only withstand about 1.3 kN. a. If a 140 g baseball strikes your head at 30 m/s and stops in 0.0015 s, what is the magnitude of the ball’s acceleration? b. What is the magnitude of the force that stops the baseball? c. What force does the baseball apply to your head? Explain. d. Are you in danger of a fracture if the ball hits you in the forehead? In the cheek?arrow_forwardA 10 kg box is on the horizontal surface with an exerting force of 95.3 N to start a box in the horizontal surface. a. Calculate the coefficient static friction. b. If the box continues to move with an acceleration of 1.71 m/s. What is the kinetic friction.arrow_forwardAn early submersible craft for deep-sea exploration was raised and lowered by a cable from a ship. When the craft was stationary, the tension in the cable was 6000 N. When the craft was lowered or raised at a steady rate, the motion through the water added an 1800 N drag force.a. What was the tension in the cable when the craft was being lowered to the seafloor?b. What was the tension in the cable when the craft was being raised from the seafloor?arrow_forward
- A box of mass ?= 5.00 kg is at rest on a horizontal rough surface. The coefficients of static friction and kinetic friction between the surface and the box are μ?= 0.450 and μ?= 0.400, respectively. Then, a horizontal force ?⃗ is exerted on the box. a. If the magnitude of the force ?⃗ is 12.0 N, what is the magnitude of the friction force on the block? b. If the magnitude of the force ?⃗ is 25.0 N, what is the magnitude of the acceleration of the block?arrow_forwardA monkey of mass m = 10.0 kg is holding on to two vines each of length l = 3.00 m. The vines form an angle with the horizontal of 40.0 degrees (see figure). The monkey is not moving and the vines are considered massless and not stretchable. a. What is the distance d between the mounting points of the vines at the top? b. Draw a free body diagram of the monkey and indicate all forces.arrow_forwardA 350 g block of wood on a horizontal plane is fastened to a cord passing over a frictionless pulley and attached to a 265 g load. The coefficient of kinetic friction between block and plane is 0.45 a. Determine the acceleration of the system after it is set in motion. b. What is the force in the chord?arrow_forward
- A picture of mass m = 11 kg is hung on a wall from a hook with a piece of wire. The picture hangs level and is centered on the hook. The tension in the wire is the same on both sides of the hook. Each section of wire makes the same angle with the horizontal. Refer to the figure. a. Choose the best free body diagram. b. Initially the picture is hung with a short wire, such that θ1 = 13°. What is the tension in the wire, in newtons. c. The wire is replaced with a longer wire. The picture now hangs with θ2 = 49°. What is the new tension in the wire, in newtons.arrow_forwardA person lying in a bunk bed pushes a 5 kg block across the ceiling. He uses a force P of magnitude 80 N and angle θ = 70°. The coefficient of kinetic friction between the block and the ceiling is 0.4. a. Draw the free body diagram of the block. b. What is the magnitude and direction of the block’s acceleration?arrow_forwardThe pair of pulleys is used to lift a 40-kg block 0.25 m. The constant upward acceleration of the block during the lift is +2.5 m/s^2, and the pulleys and rope have negligible inertia and negligible friction. A. What is the tension in the pulling rope? Express your answer with the appropriate units. B. What is the tension in the rope from which the block hangs? Express your answer with the appropriate units. C. Determine the magnitude of the force exerted by the upper mount on the top pulley. Express your answer with the appropriate units. D. How much work is done by the person pulling the rope in lifting the block 0.25 mm? Express your answer with the appropriate units. E. By how much does the kinetic energy of the block change in this process? Express your answer with the appropriate units. F. How much work is done on the block by the rope attached to it? Express your answer with the appropriate units. G. How much work does the ceiling do in this process? Express your answer with the…arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning