Moving About - Force: (1 Viewer)

[ADrew]

Hey guys. Struggling with these two problems. Help would be very much appreciated. I think they involve vectors, which is probably the reason im struggling:

1) A 1000kg plane is travelling north at 40m/s. Its subjected to a force of 100N east for 30 seconds. What is its final velocity?

2) A 2kg trolley is moving north at 2m/s. Five seconds later it is moving south at 3m/s. During that time a constant force is acting on the trolley. What is the value of this force?

 

[nightweaver066]

Initial eastward velocity is 0.
Use Newton's 2nd law, F=ma to determine acceleration.
Calculate the eastward velocity using v = u + at.
Use vector addition to find resultant velocity. (pythagoras theorem to find the resultant speed and some trigonometry to find the angle)

Use a = (v-u)/t remembering the velocities are in opposite directions
Then use Newton's 2nd law, F = ma to determine the force (Remember direction, force is a vector)

 

[ADrew]

Thank you heaps!!