Lab 7

Conservation mechanical energy

KE=>PE

Kinematic x(t)

x(t)=xi+vi(t)

Is KE conserved during ballistic pendulum collision?

kinetic energy is not conserved due to collision forces, constraint forces, air resistance, and gravitational forces, the decrease of KE is transferred to PE.

Dissipative forces

kinetic friction and collision forces

How do you use momentum to find resultant velocity of an inelastic collision?

m1v1+m2v2=(m1+m2)V

Mechanical energy

Emech=GravitationalPotentialEnergy + KineticEnergy

What principles can you use to find the speed of the block at the base of the incline?

Conservation of Mechanical Energy and Kinematics

Is ball block collision elastic or inelastic?

Inelastic because the system becomes one mass at one velocity so KE is not conserved.

How do you use conservation of mechanical energy?

KE=PE .5mv^2=mgh

If an inelastic collision takes place, during the collision, what is conserved?

Momentum and Energy

If a completely elastic collision takes place, during the collision, what is conserved?

Momentum, Mechanical Energy, and Energy

A steel rod with block on the end is swinging upward, are there any external forces, besides air resistance, that do work on the system?

No, there are no nonconservative external forces, (possibly a little friction at rotation point).

A steel rod with block on the end is swinging upward, are there any non-conservative forces that do not do work the block?

Tension does not do work because the rod is steel.

How well do conservation principles of linear momentum and mechanical energy apply?

They do not apply well because of forces like tension and friction.

Is linear momentum conserved immediately before and after a a ballistic pendulum collision?

Yes the short time before and after it is.

h- height of a pendulum l- string length x- angle to neutral position

h=L-Lcosx

Constraint forces

tension, normal force, static friction

Initial velocity

vi=sqrt(R^2g/2H)

Kinematic y(t)

y(t)=yi+vi(t)-.5gt^2