Speed, velocity and accelaration

[billytonydavies]

Just need some help with the following questions which are probably very easy to you guys. Here are the 2 questions I need help with.

1). A boat sails 150m due south and 150m due east. This takes a total time of 45s. Calculate (i). the boat's average speed and (ii) the boats average velocity.

2). A car traveling at 10 ms -1 due north speeds up uniformly to a velocity of 25 ms-1 in 5 s. Calculate the acceleration of the car during these 5 seconds. Let the direction of the motion of the car, due north, be taken as the positive (+) direction.

Thanks in advance.

Billy. Can email me at: annaporcel@talk21.com

[AKG]

1) Average speed = Total Distance/Total Time = 300m/45s = 6.7m/s
Average velocity = Total Displacement/Total Time = (150m[south] + 150m[east])/45s
= 150\sqrt{2}m[south-east]/45s = 4.7m/s[south-east]

2) a = (v2 - v1)/t = (25 - 10)/5 = 3 m/s -2

[billytonydavies]

Thanks very much for your help. Much appreciated.