The helium used to fill birthday balloons doesn’t come out of the air, but from out of the ground. Some of the gas might escape from the ground into the

atmosphere, but the majority of it is trapped in Earth’s crust. Based on what you have learned in today’s lab, give a reasonable explanation for the presence of helium gas in Earth’s crust.

In raising a 6200-n piano with a pulley system, the movers note that, for every 2.2 m of rope pulled down, the piano rises 0.12 m . ideally, find the force required to lift the piano.

Question 7 [2 marks] in the circuit below, the electromotive force generated by the battery is e = 6.0 v, and the resistances are r1 = r4 = 1.0 q, r2 = r3 =2.0 q. r. the power delivered by the battery to the circuit is closest to a. 6 w в. 12 w с. 15 w d. 18 w e. 20 w final exam autumn 2014 page 5 of 9 68037 physical modelling faculty of science [2 mark] question 8 with reference to question 7, the current through resistor r2 is closest to a. 1 a в. 2 а c. 3 a d. 4 a e. 6 a

Using the free-body diagram, calculate the net force acting on the sled. is the sled in a state of dynamic equilibrium?