Straighter Line Physics Qs and As

When a small car pulls a trailer for a move, which of the following explains why the trailer moves? CORRECT ANSWERS: While the force of the trailer on the car is equal and opposite to the force of the car on the trailer, the total of all forces acting on the car are unbalanced. Suppose you are driving a car at a constant speed of 40 mph in a straight line. All of a sudden the road curves to the right but you manage to keep driving at exactly the same speed. Which of the following statements is correct? CORRECT ANSWERS: There was a net force acting on the car. Given the vectors C=2i^+7j^ and D=14i^+38j^D, find the angle θ between them. CORRECT ANSWERS: θ=4∘ Match each of the following descriptions of motion with the appropriate graph. resting uniform motion accelerated motion oscillating motion CORRECT ANSWERS: 1-B; 2-D; 3-C; 4-A A juggler is juggling 3 balls. If she throws them 2.4 m in the air at an angle of 80° relative to the horizontal, what is the time between throws? (You should ignore air drag and the time it takes for the juggler to move balls from one hand to the other.) CORRECT ANSWERS: 0.47 s Given the vectors C=1.5i^+6.2j^ and D=4.4i^+7.3j^, calculate the magnitude of their vector product. CORRECT ANSWERS: 16.3 Which of the following statements concerning friction between the surfaces of two objects is correct? CORRECT ANSWERS: The force of friction mostly depends on the nature of the two surfaces. A 2.5 kg object is suspended from a spring with a spring constant of 48 N / m. The mass is pulled 0.25 m downward from its equilibrium position and released. Which of the following is the maximum kinetic energy of the object? CORRECT ANSWERS: 1.5 J Why is (vector) A⋅ (vector) B =AxBx+AyBy CORRECT ANSWERS: All the cross-terms are equal to zero. Consider a mass m that is attached to a rope such that the mass is in uniform circular motion. Which of the following is the magnitude of the centripetal force? CORRECT ANSWERS: mv 2/r Which of the following applies to the tangential velocity v of uniform circular motion? CORRECT ANSWERS: constant speed but not constant velocity