Equations Flashcards
Power
Force x Velocity
Force
Mass x Acceleration
What is the units for power?
Watts (W)
How many watts is 1 kW?
1000W
What is the units for a force?
Newtons (N)
Work done
Force x Distance Moved
Power
The rate of doing work (Work Done / Time)
How many kg is 1 tonne?
1000kg
Newton’s law of restitution
speed of separation of particles / speed of approach of particles = e
What does the constant e represent?
the coefficient of restitution between the particles.
0 ≤ e ≤ 1.
What does it mean when e=1?
The speed of separation is the same as the speed of approach. It is a perfectly elastic collision.
What does it mean if e=0?
The particles join together on impact. It is a perfectly inelastic collision.
What is the principle of conservation of linear momentum?
m1u1 + m2u2 = m1v1 +m2v2
For a direct collision, what can Newton’s law of restitution be written as?
speed of rebound / speed of approach = e
What value of g do we use?
9.8 ms-2
How do you calculate the loss of kinetic energy due to impact?
(0.5m1u1² + 0.5m2u2²) - (0.5m1v1² + 0.5m2v2²)
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How do you calculate momentum?
Mass x velocity
How do you calculate impulse?
Force x time
or
mv-mu (final momentum - initial momentum)
Work done against gravity
mgh
Kinetic energy
0.5 x mass x velocity²
Potential energy
mass x gravity x height
How do you calculate work done by a force which accelerates a particle horizontally?
Change in kinetic energy
What is the principle of conservation of mechanical energy?
When no external forces (other than gravity) do work on a particle during its motion, the sum of the particle’s kinetic energy and potential energy remains constant.
