An object falls freely from rest through a vertical distance of 44 An object falls freely from rest through a vertical distance of 44.0 m in a time of 3.0 s. What value should be quoted for the acceleration of free-fall?   A. 9.778 m s-2 B. 9.780 m s-2 C. 9.78 m s-2 D. 9.8 m s-2 Multiplication or division: (3sig.fig.)x(2sig.fig) = 2sig.fig (3sig.fig.)/(2sig.fig) = 2sig.fig D.

400 nm → 0.75x1015 Hz D. 700 nm → 0.43x1015 Hz and then use 𝑐=f 2. What is the order of magnitude for the frequency of visible light? 10–15 Hz 10–7 Hz 109 Hz 1015 Hz Either you know visible light frequency range, or you know visible light wavelength range: 400 nm → 0.75x1015 Hz 700 nm → 0.43x1015 Hz and then use 𝑐=f D.

3. A woman walks due north at 1 m s–1 before turning through an angle of 900 to travel due east without any change in speed. What is the change, if any, of her velocity? No change 1ms–1 to the west 2 ms–1 to the north east 2 ms–1 to the south east 𝑣 2 𝑣 1 D. ∆ 𝑣 = 𝑣 2 − 𝑣 1 = 𝑣 2 +(− 𝑣 1 ) 𝑣 2 ∆ 𝑣 − 𝑣 1

5. A parachutist jumps out of an aircraft and falls freely for a short time, before opening his parachute. Which graph shows the variation of the acceleration a with time t of the parachutist from the time he leaves the aircraft until after the parachute is completely open? A. B. Before the parachute opens 1. When the skydiver jumps out of the plane he accelerates due to the force of gravity pulling him down. 2. As he speeds up the upwards air resistance force increases. He carries on accelerating as long as the air resistance is less than his weight. 3. Eventually, he reaches his terminal speed when the air resistance and weight become equal. B. C. D. After the parachute opens 4. When the parachute opens it has a large surface area which increases the air resistance. The force of air resistance becomes much, much greater than the force of gravity. The net force on the descending skydiver now has an acceleration that points upward - negative acceleration or deceleration. Gradient becomes strongly negative when the parachute is opened. This causes a rapid decrease in the skydiver's velocity. 5. As the parachutist slows down, his air resistance gets less until eventually it equals the downward force of gravity on him (his weight). Once again the two forces are equal and he falls at terminal speed. This time it's a much slower terminal speed than before.

B. 𝑚 𝑣 𝑓 _ 𝑚 𝑣 𝑖 𝑚 𝑣 𝑓 _ 𝑚 𝑣 𝑖 = = + Or one can decompose both vectors into components (easier) Horizontal components will be the same so result of subtraction is zero. Final vertical component – initial vertical component is equal to 2×(final vertical component)

D. As the block is pulled with greater and greater force, but still doesn’t move, form Newton’s first law it is obvious that static frictional force increases. It is maximum at the moment, when the block starts to move: 𝑠𝑡𝑎𝑡𝑖𝑐 𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑓𝑜𝑟𝑐𝑒:𝐹 𝑓𝑟 ≤ 𝜇 𝑠 𝐹 𝑛 → 𝐹 𝑓𝑟 𝑚𝑎𝑥 = 𝜇 𝑠 𝐹 𝑛 Once the block starts to move, kinetic friction takes over. It is constant force ( 𝐹 𝑓𝑟 = 𝜇 𝑘 𝐹 𝑛 , but 𝜇 𝑘 > 𝜇 𝑠 )

8. The pound is a unit of mass equivalent to 0. 454 kg 8. The pound is a unit of mass equivalent to 0.454 kg. It is used in a limited number of countries but is rarely used by modern scientists. Which statement is correct? Scientists cannot be sure that all other scientists will be able to work in pounds. The pound cannot be defined precisely enough to be used. The pound is too large a unit to be used for most masses. The pound cannot be divided into metric portions. A. Everything can be converted into metric system. Just divide by 10, then again by ten…..

𝑀+𝑚 𝑣=𝑀𝑉 → 𝑉= 𝑀+𝑚 𝑀 𝑣 D.

C. 𝑐= 𝑒𝑛𝑒𝑟𝑔𝑦 𝑚∙∆𝜃 = 𝑝𝑜𝑤𝑒𝑟∙𝑡𝑖𝑚𝑒 𝑚∙∆𝜃 = 12 0.2 × (200−0) (26−20) =60 200 6 =2000 𝐽 𝑘𝑔 −1 𝐾 −1

B.

C. It is not in SL curriculum – but one never knows. In the case of changing P(V), work is the area bellow graph p(V):

13. The diagram shows a simple pendulum undergoing simple harmonic motion between positions X and Z. Y is the rest position of the pendulum. 𝐹=−𝑚𝑔 𝑠𝑖𝑛𝜃 v = 0 v = 0 Which describes the magnitude of linear acceleration and linear speed for the pendulum bob? v = vmax 𝑎= 𝑎 𝑚𝑎𝑥 → 𝑎=0 𝑎= 𝑎 𝑚𝑎𝑥 ← 𝐹= 𝐹 𝑚𝑎𝑥 → 𝐹=0 𝐹= 𝐹 𝑚𝑎𝑥 ← Linear acceleration Linear speed A. zero at Y zero at Y B. maximum at X and Z zero at X and Z C. maximum at X and Z maximum at X and Z D. zero at X and Z maximum at X and Z linear means along the arch B.

B. 14. Some of the properties that can be demonstrated using waves are I. refraction II. polarization III. diffraction. Which properties can be demonstrated using sound waves? A. I and II only B. I and III only C. II only D. III only B. polarization happens only with transverse waves, and sound is longitudinal wave

15. The amplitude of a wave at a certain distance for a source is A and its intensity is I. At this position the amplitude increases to 4A. What is the intensity of the wave? A. I B. 2I C. 4I D. 16I 𝐼= 𝑃 4𝜋 𝑑 2 power is 𝑒𝑛𝑒𝑟𝑔𝑦×𝑡𝑖𝑚𝑒. Energy is proportional to amplitude squared. Intensity is proportional to amplitude squared. D.