Answer:
8.929kg
Explanation:
The work done to place the box at tree house=350 J.
The distance from ground to tree house =4.0 m and ![g=9.8m/s^2](https://tex.z-dn.net/?f=g%3D9.8m%2Fs%5E2)
![E=mgh\\\\m=350J/(9.8m/s^2\times 4.0m)\\\\m=8.929kg](https://tex.z-dn.net/?f=E%3Dmgh%5C%5C%5C%5Cm%3D350J%2F%289.8m%2Fs%5E2%5Ctimes%204.0m%29%5C%5C%5C%5Cm%3D8.929kg)
Hence the mass of the box is 8.929kg
<span>1. Thermometer : a tool that measures temperature. Balance : used to measure the mass of an object to a know unit of mass. Compass : a tool that uses a magnetized pointer to show magnetic north. Barometer : a weather instrument that measures air pressure. Graduated Cylinder : used to measure the volume of liquids. Science Tools and Equipment<span><span>2. </span>Spring Scale : a tool that measures the pull of gravity on an object. Magnifier : a toll that lets you see things you cannot see with just your eyes. Microscope : a tool that lets you see objects that are too small to see with a magnifier. Petri dish : small, flat, clear dish used to grow mold or bacteria. Safety goggles : for eye protection when working with liquids or other materials that might get into eyes.</span><span><span>3. </span>Collection net : useful for gathering leaves and other materials needed for investigations. Test tube : a small, narrow glass tube used in an investigation. First aid : band-aids and bandages for safety. Stop watch : a tool used to measure elapsed time. Apron : protective covering for clothes. Bunsen burner : an open-flame heat source used to heat substances in an investigation.</span><span><span>4. </span>Journal : a record of your science investigation. Hot plate : a warming surface used to heat a substance in an investigation. Flask : a container with a large flat base and narrow spout used to hold liquids. Meter stick : a tool used to measure length or distance in metric units. Telescope : used to observe and study objects in space.</span><span><span>5. </span>Anemometer : a tool used to measure wind speed or velocity. Eyedropper : used to measure liquids by the drop. Gloves : protective covering for hands. Magnet : an object that attracts iron or steel.
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12km = 12000m
12000m / 4 m/s = 3000s
just under one hour