You have been called to testify as an expert witness in a trial involving a head-on collision. Car A weighs 1515 lb and was traveling eastward. Car B weighs 1125 lb and was traveling westward at 42.0 mph. The cars locked bumpers and slid eastward with their wheels locked for 19.5 ft before stopping. You have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750. How fast (in miles per hour) was car A traveling just before the collision? (This problem uses English units because they would be used in a U.S. legal proceeding.) speed of car A: mph

A car (mass 1000 kg) is traveling at 60 mph (26.82 m/s) when the driver notices a cat 50 m ahead in the road. Wanting to save the feline's life, the driver slams on the brakes and comes to a stop 2 m in front of the cat. What was the car's acceleration as it was braking?

What is the mass of the box?

A robot with fancy wheels is trained to move in two directions simultaneously. The force in the forward direction is 10 N and the force in the horizontal direction is 8 N. If the robot starts from rest, has a mass of 75 kg and travels for 100 seconds, what is the magnitude of the robot's final displacement?

It may appear at first glance that Newton's 2nd and 3rd laws are independent claims. This, however, is not true - Newton's 3rd law is simply a consequence of Newton's 2nd law. In this problem, you will prove Newton's 3rd law for the normal contact force between two objects, using only Newton's 2nd law. Consider two blocks with masses m₁ and m₂ in contact, with external forces F₁ and F2 applied, as shown in the figure. The free body diagram for each block is also given, with internal forces fa and f, as shown. F₁ F₁ fa fb ΣF = ΣF = m₁ m2 Submit F₂ Complete the equations of motion for the entire system, as well as blocks 1 and 2 individually. Note, the forces have a signed magnitude, where positive values correspond to the positive x-direction ΣF= = (m₁ + m₂) a = m₁ a = m₂ a Use the above equations to write fa in terms of only fr: fa = m₁ You have used 0 of 4 attempts m₂ F₂ Save Calculator

In a performance test, each of two cars takes 9.6 s to accelerate from rest to 25 m/s. Car A has a mass of 1406 kg, and car B has a mass of 1910 kg. Find the net average force that acts on (a) car A and (b) car B during the test. (a) F (b) F= = i

Dr. Miller is conducting an experiment. He has a stack of books on a table which is frictionless and flat. He applies a force F on the stack, and finds that it accelerates at 3.0 m/s². He then adds a book to the stack. This is a physics textbook that has a mass of 1.0 kg. He then applies the same force F on the stack and finds that now the stack accelerates at 2.0 m/s². What was the mass of the original stack of books? a) 1.0 kg Ob) 2.0 kg c) 3.0 kg O d) none of the above

A semi is traveling down the highway at a velocity of v = 27.5 m/s. The driver observes a wreck ahead, locks his brakes, and begins to slide. The truck has mass m and a coefficient of kinetic friction between the tires and the road of μk = 0.16. Write an expression for the sum of the forces in the x-direction for the truck while braking? Using the results from Part (a), input an expression for the truck's acceleration, at, while breaking? What is the magnitude of the acceleration in m/s2?  How far does the truck travel, d in meters, before stopping?

In the figure here, block 1 of mass 2.2 kg and block 2 of mass 3.4 kg are connected by a string of negligible mass and are initially held in place. Block 2 is on a frictionless surface tilted at 0 = 23 °. The coefficient of kinetic friction between block 1 and the horizontal surface is 0.25. The pulley has negligible mass and friction. Once they are released, the blocks move. What then is the tension in the string? Number i Unit

Newton's Third Law. A student in elementary physics finds himself in the middle of a large ice rink with a small but finite coefficient of friction between his feet and the ice. He has been taught Newton's Third Law. Since the law says that for every action there is an equal and opposite reaction, all forces add up to zero. Therefore he assumes that there will be no force possible to accelerate him toward the side of the rink and so he must stay at the center. (a) How do you tell him to get to the side?