Kinematics

Question 1

A paraglider P of mass 95 kg is pulled by a wire attached to a boat,
The wire makes an angle of 25° with the horizontal water surface.
Acceleration of P is 1.4 m s^-2.
The tension in the wire at time t = 5.0 s is 280 N.
1. the vertical lift force F supporting P,
2.the force R due to air resistance acting on P in the horizontal direction.

Answer 1

1. F = vertically downwards component of tension + weight
   F = 280sin25 + (95×9.81)
2. a= 1.4 ms‐²
   Fr = ma = 95 x 1.4
   Fr = Ht(horizontal component of tension) - Fa.r(air resistance opposing the motion)
   133 = 280cos25 - R
   R = 120.8 N

Question 2

Describe the acceleration of a ball as it freefalls in air until it reaches terminal velocity

Answer 2

1. Initial acceleration is 9.81 ms‐².
2. Acceleration decreases gradually
3. Final accn is zero

Question 3

From time t = 12 s, the velocity of each car remains constant at its value at t = 12 s.
Determine the time t at which car Q passes car P. [Steps no values. Also you have a v-t graph for both cars]

Answer 3

1. Calculate relative speed between the two cars
2. Find distance between them at t 12s.
3. Use s = d/t