A tethered ball moves in a horizontal circle of radius 2 m. It makes one revolution in 3 s.

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Dayna Foster
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1 Circular motion A tethered ball moves in a horizontal circle of radius 2 m. It makes one revolution in 3 s. Find its acceleration. (a) 8.76m/s 2 (b) 8.76m/s 2 (c) 8.76m/s 2 (d) 62.3m/s 2 direction outwards direction inwards direction same as velocity direction outwards a = v2 r (e) (f) 62.3m/s m/s 2 direction inwards direction same as velocity

2 Circular motion A tethered ball moves in a horizontal circle of radius 2 m. It makes one revolution in 3 s. Find its acceleration. (a) 8.76m/s 2 (b) 8.76m/s 2 (c) 8.76m/s 2 direction outwards direction inwards direction same as velocity (d) (e) (f) 62.3m/s m/s m/s 2 direction outwards direction inwards direction same as velocity

3 Circular motion A tethered ball moves in a horizontal circle of radius 2 m. It makes one revolution in 3 s. Find its acceleration. v = 2 r T = 2 (2 m) 3s =4.19 m/s a = v2 r = (4.19 m/s)2 2m =8.76 m/s 2 a = v2 r

4 Circular motion What are the period and speed of a person on a carousel if the person has an acceleration with a magnitude of 0.8m/s 2 when she is standing 4.0m from the axis? (a) 14s, 1.8m/s (b) 7.9s, 3.2m/s (c) 23s, 1.8m/s (d) 0.7s, 0.4m/s

5 Circular motion What are the period and speed of a person on a carousel if the person has an acceleration with a magnitude of 0.8m/s 2 when she is standing 4.0m from the axis? (a) 14s, 1.8m/s (b) 7.9s, 3.2m/s (c) 23s, 1.8m/s v = p ra T = 2 r v (d) 0.7s, 0.4m/s

6 Circular motion What are her acceleration magnitude and speed if she then moves to a distance of 2.0m from the carousel centre and the carousel keeps rotating with the same period? (a) 0.29m/s, 0.04m/s 2 (b) 1.1m/s, 0.61m/s 2 (c) 1.8m/s, 0.8m/s 2 (d) 0.9m/s, 0.41m/s 2

7 Circular motion What are her acceleration magnitude and speed if she then moves to a distance of 2.0m from the carousel centre and the carousel keeps rotating with the same period? (a) 0.29m/s, 0.04m/s 2 (b) 1.1m/s, 0.61m/s 2 (c) 1.8m/s, 0.8m/s 2 (d) 0.9m/s, 0.41m/s 2 v = 2 r T a = v2 r

8 Forces Newton s First Law But a rolling ball comes to a stop. Why? (A) (B) (C) (D) there always has to be a continual force to keep moving there is a force acting that stops the ball because rolling is a different kind of motion Newton s laws don t always apply

9 Forces Newton s First Law But a rolling ball comes to a stop. Why? (A) (B) (C) (D) there always has to be a continual force to keep moving there is a force acting that stops the ball because rolling is a different kind of motion Newton s laws don t always apply

10 Forces Newton s First Law Apollo 11 landed on the moon in Some people have claimed the moon landing was fake. One reason they give is that the American flag waves, yet there is no wind on the moon. Why is this reason invalid? (A) There is wind on the moon. (C) Oh my God! There was no moon landing! (B) The flag moves as the astronauts set it down, and doesn t stop. (D) The flag doesn t wave, the video was bad.

Forces Newton s First Law Apollo 11 landed on the moon in 1969. Some people have claimed the moon landing was fake.

11 Forces Newton s First Law Apollo 11 landed on the moon in Some people have claimed the moon landing was fake. One reason they give is that the American flag waves, yet there is no wind on the moon. Why is this reason invalid? (A) There is wind on the moon. (C) Oh my God! There was no moon landing! (B) The flag moves as the astronauts set it down, and doesn t stop. (D) The flag doesn t wave, the video was bad.

Forces Newton s 2nd Law A force produces an acceleration of 150 m/s 2 150 m/s 2 50 m/s 2 0.015kg?

12 Forces Newton s 2nd Law A force produces an acceleration of 150 m/s m/s 2 50 m/s kg? The same force gives a 2nd can an acceleration of 50 m/s 2. What is the mass of the second can? (a) kg (b) kg (c) kg (d) 22.2 kg

13 Forces Newton s 2nd Law 150 m/s 2 50 m/s kg? The same force gives a 2nd can an acceleration of 50 m/s 2. What is the mass of the second can? (a) kg (b) kg (c) kg (d) 22.2 kg

Forces Newton s 2nd Law 150 m/s 2 50 m/s 2 0.015kg? The same force gives a 2nd can an acceleration of 50 m/s 2.

14 Forces Newton s 2nd Law 150 m/s 2 50 m/s kg? The same force gives a 2nd can an acceleration of 50 m/s 2. What is the mass of the second can? F = m 1 ā 1 = m 2 ā kg 150 m/s 2 = m 2 50 m/s 2 m 2 = kg 150 m/s2 50 m/s 2

Topic 6 Circular Motion and Gravitation

Topic 6 Circular Motion and Gravitation Exam-Style Questions 1 a) Calculate the angular velocity of a person standing on the Earth s surface at sea level. b) The summit of Mount Everest is 8848m above