- A 300 g sample of thorium -234 has a half-life of 24 days. The mass of thorium, in grams, that remains after t days can be modelled by M(t)=300((1)/(2))^(t)/(24) What mass will remain after 31 days? a) 122.5 g b) 193.75 g c) 1508 d) 177 .5g
- 20) Use the Electrostatic Series to determine the charge that two neutral objects would have after they are rubbed together. If nothing happens, then state "nothing happens." [4 marks] a) Plastic is rubbed with hair. Plastic becomes __ Hair becomes __ b) Zinc is rubbed with aluminum. Zinc becomes __ Aluminum becomes __ c) Glass is rubbed with rubber Glass becomes __ Rubber becomes __ d) Of the 3 situations above, circle the letter of the materials that will produce the greatest charge difference?
- 12. A system of masses is connected by a light cord passing over a pulley as shown in the diagram. When released, the 25 kg mass drops. The angle of the incline is 40.0^circ Calculate the tension in the cord. [5 marks]
- 9.Extended Response: A box is being pushed across a rough surface. The applied force is increased, and the box starts moving faster. Explain this scenario in terms of balanced and unbalanced forces, friction and net force __ Bonus Questions: 10. A box is being pushed with a force of 50 N to the right, but it does not move Explain why the box remains stationary What can be done to make the box move? 11. You are pulling a sled with a force of 30 N at an angle of 30 degrees above the horizontal. How does the angle of the force affect the normal force and friction acting on the sled?
- 19) Rice Krispies are very lightweight and electrically neutral. If a negatively charged rod is placed in with the puffs. they will be attracted to the rod. However, after a short period of time they fly off in all directions. Why does this happen? [2 marks]
