Chapter 5 review


    Quantitative problems
      Section 5.1
      1. Which contains more matter: 100 lb of stone or 100 N of stone? Express both quantities in kilograms to justify your answer.
      2. What is the weight of a 20 kg sack of cement?
      3. There are 16 ounces in a pound. Calculate the equivalent of a one ounce force in newtons.
      4. Forces on a marionette
      5. What is the normal force between a 5 kg puppet and the floor if the puppet is attached to a string that applies 30 N of force upward?
      6. Draw a free body diagram for the board
      7. Draw a free-body diagram of the board shown in the diagram above with all the forces acting on it. You may assume the crate is at the center.
      8. You have 10 kg of coconuts.
        1. How many kilograms of bananas have the same mass?
        2. How many pounds is this?
      9. Forces are often classified by the number of “g”s. For example, a 1g force is equal to an object’s weight, a 2g force is twice an object’s weight, and so on. If a person has a mass of 50 kg, then what force would be equivalent to 7g’s? Give your answer in pounds and newtons. This is approximately the force a pilot can withstand before losing consciousness.
      10. Draw a free-body diagram of the dumbbell
      11. Draw a free-body diagram of the dumbbell shown in the picture above. Be sure to include normal forces. Assume the dumbbell is not moving.
      12. Easy What is the weight of a 50 kg woman at the top of Jupiter’s atmosphere, where g = 24.8 N/kg? Give your answer in both newtons and pounds.
        Section 5.2
        1. What is the mass of a man who accelerates 4 m/s2 under the action of a 300 N net force?
        2. What is the normal force when a 40 kg person jumps and is accelerating at 3 m/s2 upward while in contact with the ground?
        3. What is the force required to accelerate a 180,000 kg blue whale at 3 m/s2?
        4. There is a tug-of-war game going on. There are 5 people on each team with an average mass of 60 kg. What is the acceleration if there is a net force of 400 N to the right?
        5. How far will a 600 kg boat travel in 12 s if there is a constant 900 N force on it and it starts from rest?
        6. A 10 N net force is applied to an object, which then accelerates at 4 m/s2. What is the mass of the object?
        7. A cart is moving at 9 m/s on a frictionless surface. Kayla pushes the front end of the cart with a force of 60 N, while Kristofer pushes from the back with a force of 60 N. How fast is the cart moving after 5 s?
        8. What net force is required?
        9. Easy What net force is required to give a 4 kg rock an acceleration of 2 m/s2?
        10. Medium Bathroom scales read the normal force that is exerted against the floor. What would a scale read when a 100 kg man is in an elevator accelerating upward at 1.2 m/s2? What would it read when the man is accelerated downward at 1.8 m/s2?
        11. Draw a free-body diagram for the box
        12. Medium Draw a free-body diagram for a 4 kg box sitting on a table. The box is accelerating at a rate of 4 m/s2 to the right, and there is a friction force of 12 N.
        13. Medium One important part of testing a car is seeing how fast it can brake. A 1,100 kg car is traveling at 15 m/s when the brakes are suddenly applied. How far a distance will it travel if the brakes can exert a force of 6,000 N?

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