# Mechanics - Physics

- Created by: th13114
- Created on: 07-11-18 08:06

MECHANICS

**Vectors and Motion**

when drawing velocity vectors vi is drawn negative as v= vf-vi

In flight horizontal motion is constant as there are ni extrenal forces in the horizaontal direction as air resistnace is negligable. When going up vertical velocity is decreasing as the weught force/ gravity is accelerating the object downwards. This gravity/weight force is opposite to the motion so the object slows down. At the objects highest point its velocity is zero. When going back down the object accelerates downward as the motion is going with the weight/gravity force. The veloicty at the moment just before it hits the ground is the sam e as the velocity of the object just after it is released.

**Forces**

In spring constant questions a larger spring constant means the spring is harder to stretch. The negative sign inthe equation indicates that the force is opposite to the direction of the extension.

In a force diagram there are 4 main forces, thrust forward, friction backwards, support upwards and weight downwards. When net force is 0N then the object is at a constant speed.

When there is a diagonal force not all of this force is used in acceleration. Acceleration is the forward cimponent of the vector. The forward component is less than the diagonal component as some of the force is upward.

In centripital acceleration the object is constantly accelerating inward and has a velocity that is a tangent to the curve the object is on. There is acceleration here because even though the object is travelling at a constant speed it is changing its direction of motion continuously, this means it is changing velocity. A change in either speed…

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