#### Review of solving problems on gravity

(9 Questions)** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

Ralph had the following calculations:

\begin{array}{lll} m_2 &=& 4 \times 10^{-6} \times \frac{1}{6.67 \times 10^{-11} \times 10} \\ &=& \frac{4}{6.67} \times 10^{-5} \times 10^{11} \\ &=& 5.99 \times 10^6 \\ \end{array}

Therefore, m_2 \approx 6,000,000 kg

Rachel had the following calculations:

\begin{array}{lll} m_2 &=& \frac{4 \times 10^{-6} \times 1}{6.67 \times 10^{-11} \times 10} \\ &=& \frac{4 \times 10^{-6} }{6.67 \times 10^{-10}} \\ &=& 5.99 \times 10^3 \\ \end{array}

Therefore, m_2 \approx 6,000 kg

Who is correct?

**A**

**B**

**C**

**D**

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

Ralph decided to use F = G \frac{m_1 m_2}{d^2} to find m_2 .

He had the following steps:

\begin{array}{lll} F &=& G \frac{m_1 m_2}{d^2} \\ F d^2 &=& G m_1 m_2 \\ \frac{F d^2}{G m_1} &=& m_2 \\ \end{array}

Meanwhile, Rachel had the following steps:

\begin{array}{lll} F &=& G \frac{m_1 m_2}{d^2} \\ F d^2 &=& G m_1 m_2 \\ F \frac{d^2}{G m_1} &=& m_2 \\ \end{array}

Who is correct?

**A**

**B**

**C**

**D**

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

What is the given value of d in standard metric units in the diagram? DON'T ENTER UNITS.

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

The value of F in the diagram is 4 \times 10^{-6} N.

**A**

**B**

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

With how much force is the spherical flask pulling the lead ball towards itself?

**A**

**B**

**C**

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

What are the known and unknown variables in the problem?

**A**

**B**

**C**

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

What is the value of m_1 in standard units in the diagram? DO NOT ENTER UNITS.

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

Is the information provided sufficient for you to find the answer?

**A**

**B**

** The problem:** "In a Von Jolly experiment, very sensitive force measurement tools were used to measure the force F on a spherical flask of mercury with a mass of 10 kg, from a large lead ball 1 m directly below the flask. The force on the object was measured to be 4 \times 10^{-6} N . How heavy was the lead ball? Note that the F in the diagram is force on the spherical flask from the lead ball."

In the problem, what are you being asked to find out?

**A**

**B**