Concept explainers
A crash test is performed between an SUV A and a 2500-lb compact car B. The compact car is stationary before the impact and has its brakes applied. A transducer measures the force during the impact, and the force P varies as shown. Knowing that the coefficients of friction between the tires and road are
(a)
The time at which the compact car starts moving.
Answer to Problem 13.137P
Time at which the compact car starts moving
Explanation of Solution
Given information:
Weight of compact car B is equal to
“A force acting on a particle during a very short time interval but large enough to produce a definite change in momentum is called an impulsive force.”
Impulse momentum principle for impulsive motion is defined as:
Calculation:
Apply impulse momentum principle.
Substitute,
Find Friction force,
The force during impact P varies,
At
Substitute in equation 1:
Conclusion:
The time when the compact car starts moving is calculated by putting the values of the weight of the car and friction force in the momentum principle equation.
(b)
The maximum speed of the car
Answer to Problem 13.137P
Explanation of Solution
Given information:
Weight of compact car B is equal to
“A force acting on a particle during a very short time interval but large enough to produce a definite change in momentum is called an impulsive force.”
Impulse momentum principle for impulsive motion is defined as,
Calculation:
Find the friction factor when moving,
At
But we know that,
Apply impulse momentum principle,
Substitute,
Therefore,
Conclusion:
The maximum speed is equal to
(c)
The time at which car comes to stop
Answer to Problem 13.137P
Explanation of Solution
Given information:
Weight of compact car B is equal to
“A force acting on a particle during a very short time interval but large enough to produce a definite change in momentum is called an impulsive force.”
Impulse momentum principle for impulsive motion is defined as,
Calculation:
To find the stopping time,
Apply impulse momentum principle,
Therefore,
Conclusion:
The car comes to stop at
Want to see more full solutions like this?
Chapter 13 Solutions
Vector Mechanics for Engineers: Dynamics
- Figure 1 of 1 > Y Part A If the force exerted on cable AB by the motor is F= (100 3/2) N, where t is in seconds, determine the 55-kg crate's velocity when t=6s. The coefficients of static and kinetic friction between the crate and the ground are = 0.38 and 0.30, respectively. Initially the crate is at rest. (Eigure 1). Express your answer to three significant figures and include the appropriate units. HÅ 28.7 Submit m S Previous Answers Request Answer ?arrow_forwardTwo blocks are joined by an inextensible cable as shown. The mass of block A is 196.1 kg and the mass of block B is 260.9 kg. If the system is released from rest, determine the acceleration (in m/s? ) of block B. Assume that the coefficient of friction between block A and the plane is uk = 0.45 and that the pulley is weightless and frictionless. Round off only on the final answer expressed in 3 decimal places. Use g = 9.81 m/s? blocks.png .. Aarrow_forward1. A small object of mass m is located on the surface of the disk with radius R if the magnitude of the coefficient of static friction between the object and the disc is u and the disc rotates with a certain angular speed so that the object of mass m slides from the disc which is at a height h. Prove that the horizontal distance traveled by the object is x = JuR2h 2. A child of mass 80 kg sits on a spinning disc and begins to slide if the coefficient of friction is 0.5 and the angular velocity of the rotating disc is 10rad/s. calculate the maximum radius R provided that the child can still sit and remain on the spinning disc? Compare your answer with the manual solution and use Matlab A beautiful jumper with mass m jumps from a height of 10 m (a Calculate the initial velocity V at the time of the diver's collision with the water and the estimated time from the time of the dive to the collision. Assume that the buoyant force of the water is able to balance the magnitude of the…arrow_forward
- The block has mass M and rests on a surface for which the coefficients of static and kinetic friction are µ̟ and µɛ respectively. A force F = kt² is applied to the cable. Given : M = 150 kg, k = 60 N/s?, H, = 0.5, H = 0.4. Which of the %3D following is/are correct? (A) The time at which block begins to slide is 2.5 sec (B) The time at which block begins to slide is 1.5 sec (C) Acceleration of block at t = 5 sec is 16 m/s? (D) Acceleration of block att = 5 sec is 6 m/s?arrow_forward1. Define both the coefficients of static and kinetic friction. Explain the 2. Blocks A, B, and C have weights of 50 kg, 25 kg, and 15 kg, respectively. Determine the smallest horizontal force P that will cause impending motion. The coefficient of static friction between A and B is µ₁=0.3, between B and C, µ₂=0.4, and between block C and the ground, μ3=0.35. A B C D teel moonine fa Parrow_forwardThe block has a mass of 140 kg and rests on a surface for which the coefficients of static and kinetic friction are Hs = 0.5 and uj. = 0.4, respectively. (Figure 1) Part A If a force F = (60t2 ) N, where t is in seconds, is applied to the cable, determine the power developed by the force when t = 5 s. Hint: First determine the time needed for the force to cause motion. Express your answer to three significant figures and include the appropriate units. µA ? P = Value Units Figure 1 of 1 Submit Request Answer Provide Feedback Next >arrow_forward
- Two cars, one with and one without ABS, are stopping from the speed v0 = 100 km/h by full braking. The first without ABS by blocking the wheels, i.e. sliding (’kinetic friction’), the second with ABS with still rolling wheels (ideal ’limiting static friction’ assumed). Determine for both cars the time and the distance for stopping if the coefficients of static and kinetic friction between pavement and tire are μ0 = 0.7 and μ = 0.45, respectively.arrow_forwardThe force of F = 45 N is applied to the cord when s= 2 m The 6-kg collar is orginally at rest. Neglect friction. (Figure 1) Figure 1.5 m 1 of 1 Part A Determine the velocity of the collar at s = 0. Express your answer to three significant figures and include the appropriate units. Enter positive value if the velocity is to the left and negative value if the velocity is to the right. V= Value Submit HA Provide Feedback Request Answer Units ?arrow_forward3. A vehicle, mass 1400 kg, passes a bend at a speed of 54 km/hr. The radius of curvature of the road is 60 m. Determine the minimum coefficient of static friction between the car tires and the road, so that the car can pass through corners safely.arrow_forward
- Question 4 Two blocks are joined by an inextensible cable as shown. The mass of block A is 192.7 kg and the mass of block B is 291.4 kg. If the system is released from rest, determine the acceleration (in m/s²) of block B. Assume that the coefficient of friction between block A and the plane is uk = 0.23 and that the pulley is weightless and frictionless. Round off only on the final answer expressed in 3 decimal places. Use g = 9.81 m/s² A Add your answer 10 Point Barrow_forwardThe two crates are released from rest. Their masses are m-40 kg and m-30 kg and the kinetic coefficient of friction between crate A and the inclined surface is pu-0.15. The angle between the inclined surface and the horizontal is 30" Figure A 30 1 of 1 > 1 ▼ Part A What is the magnitude of the velocity of the crates when they have moved 400 mm? (Eigure 1) Express your answer with the appropriate units. Submit 4 → m S Previous Answers Request Answer ? X Incorrect; Try Again; 4 attempts remaining < Return to Assignment Provide Feedbackarrow_forwardProblem 1 A 30-kg block A and 65-kg wedge B are released from rest. Neglecting friction, determine the acceleration of A relative to B. In your analysis, you must include FBDS, equating the force(s) causing the motion to the object's acceleration. B. 30arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY