Knock out the false gravity claims

Exercise and reference answers

Questions

1. Question

   Three of these statements about escape velocity are false.

   Choices

   1. Explanation

      That figure is the orbital speed at the surface

      Item

      Escape speed from the surface is 7.9 km/s

   2. Item

      Escape speed from the surface is 11.2 km/s

      Correct

      Yes

   3. Explanation

      Escape speed is root two times the orbital speed

      Item

      Escape speed is twice the orbital speed

   4. Explanation

      The mass cancels, so the same speed frees any body

      Item

      Escape speed depends on the escaping mass

2. Question

   Three of these statements about the value of g are false.

   Choices

   1. Explanation

      Earth bulges at the equator and spins, so g is smaller there

      Item

      g is larger at the equator than the poles

   2. Explanation

      Below the surface g falls as g times one minus d over R

      Item

      g grows steadily as you go deeper

   3. Item

      g at the centre of the Earth is zero

      Correct

      Yes

   4. Explanation

      G is a universal constant while g is a local acceleration

      Item

      g and G stand for the same quantity

Instructions

Three lines in each round are wrong. Tap those three and leave the one that stands.

Explanation