4. 4) Which of the following statement about work is true? (Points : 5) A) Negat

Question

4. 4) Which of the following statement about work is true? (Points : 5) A) Negative net work done on an object always reduces the object?s total energy. B) If the work done on an object by a force is zero, then either the force or the displacement must have zero magnitude. C) If a force acts downward, it does negative work. D) The formula W = Fd costheta can be used if the force is variable over the distance d. E) None of the above 5. 5) A 10 kg stone and a loo kg stone are released from rest at the same height above the ground. There is no appreciable air drag. Which of the following statements is not true? (Points : 5) A) Both stones have the same initial gravitational potential energy. B) Both stones will have the same acceleration as they fall. C) Both stones will have the same speed when they reach the ground. D) Both stones will have the same potential energy when they reach the ground. E) Both stones will reach the ground at the same time. 1. 1) A spiral spring is compressed so as to add units of potential energy to it. When this spring is instead stretched one-half of the distance it was compressed, its remaining potential energy in the same units will be (see Section 2.5 for a review of proportional reasoning) (Points : 5) A) U/2 B) U/3 C) U/4 D) 2U/3 E) 3U/4 2. 2) You slam on the brakes of your car in a panic and skid a distance on a straight and level road. If you had been traveling at half the speed, what distance would the car have skidded under the same conditions? (Points : 5) 3. 3) Consider two frictionless inclined planes with the same vertical height. Plane 1 makes an angle of 35 with the horizontal, and plane 2 makes an angle of 550 with the horizontal. Mass mi Is placed at the top of plane 1, and mass m is placed at the top of plane 2. Both masses are released at the same time. At the bottom, which mass is going faster? (Points : A) mi is faster at the bottom because of the angle is smaller. B) m is faster at the bottom because of the angle is larger. C) Neither, they both have the same speed at the bottom. D) The one with the greater mass is faster at the bottom. E) The one with the lighter mass is faster at the bottom.

Explanation / Answer

1) U = 0.5*K*A^2

U1 = 0.5*K*A^2/4

U2 = U-U1 = 0.5*K*3*A^2/4 = 3U/4

option E

2) option C

3) option C........speed v = sqrt(2*g*h)

4) option A

5) B C E are true

Related Questions

Navigate

• Browse (All)
• Browse 4
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.