Thank you,
I need explanation for June 2009, Q 10, 21 and 29
June 2008, Q 6,14, 22,26, 30, 31 (why downwards)
I feel really bad for asking so many questions.
Jun 086. Acceleration is perpendicular to the motion. We can conclude that he is talking about centripetal acceleration whereby the acceleration and the force are directed towards the center of the motion while velocity varies continuously. However speed remains constant but direction channges. this causes velocity to change.
Answer is
C14. Moment is defined as the turning effect from a point obtained from the product of the force to its perpendicular distance applied from the point.
Taking moments about the point where the ladder touches the vertical wall
Clockwise moments = Anticlockwise moments
W x a + F x h = W x 2a
Wa + Fh = 2Wa
Answer is
A22. Since it has exceeded the elastic limit there should have been plastic deformation only. However the examinator's report highlights that the limit of proportionality is not the same as the elastic limit. In other words it is referring X as the limit of proportionality and Y as the elastic limit.
Therefore if that is the case......the deformation would be only elastic.
Answer is
B26. Intensity is directly proportional to the square of the amplitude(a
2). It has been give that it is also inversely proportional to x
2where x is the distance from the source.
Hence a
2 is inversely proportional to x
2. In other words a
2x
2 = constant term.
a
12x
12 = a
22x
22(8.0)
2 x (r)
2 = A x (2r)
2therefore A = 4
Answer is
D30. At the point where the electron leaves the field.........resolve horizontally. I'll take pheta as a..
You'll get U = vcos a. Hence V =u/cos a.
Answer is
A31. Since the oil droplet gained 5 electrons its net charge became q = 5(1.6 x 10
-19)
Electric force = F = qV/d where q is the net charge, V is the potential difference across the plates and d is the distance between the plates.
F = 5(1.6 x 10
-19) x 5000/(0.8 x 10
-2)
F =5.0 x 10
-13 N
The droplet remains stationary implies the electric force is contering weight. Since weight acts downwards the electric force must be acting upwards.
Answer is
C
