D.1 Gravitational fields Quiz
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5 questions, one answer each
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1. The gravitational potential at a point is −5.0 × 10⁶ J kg⁻¹. The work needed to move a 2.0 kg mass from there to infinity is:
- A. −1.0 × 10⁷ J
- B. 2.5 × 10⁶ J
- C. 1.0 × 10⁷ J
- D. 5.0 × 10⁶ J
2. Equipotential surfaces around a spherical planet are:
- A. Radial lines
- B. Concentric spheres
- C. Parallel planes at all distances
- D. Ellipses
3. Planet X has the same radius as Earth and four times the mass. Its escape speed compared with Earth's is:
- A. the same
- B. twice as large
- C. four times as large
- D. sixteen times as large
4. A satellite in circular orbit moves to a lower circular orbit. Which is true?
- A. Ek decreases, E increases
- B. Ek increases, E decreases
- C. Ek and E both increase
- D. Ek and E both decrease
5. g as a potential gradient is written g = −ΔV/Δr. The minus sign shows that:
- A. g is a scalar
- B. the field points towards decreasing potential
- C. potential increases towards the mass
- D. g is zero at infinity