Force and Motion Flashcards
Your velocity relative to the sun ?
30 km/s
Speed
Velocity
Change in velocity
(positive or negative?)
Speed can only be positive? and never negative.
Velocity can be positive and negative.
Change in velocity can be positive or negative.
Direction of V, del V, a and P(momentum), del P with respect to force.
Force will always have same direction as (a), (del V) and (del P).
Velocity is positive/negative/increasing/decreasing will decide if V and P will have same direction as force or opposite.
Can displacement be zero?
For a moving object, distance can never be zero but displacement can be zero.
Speed of moon around earth
1000 m/s
speed of sound in air
333 m/s
speed of earth around sun
29600 m/s
Slope of distance-time graph?
a) speed
b) velocity
Speed
As distance always increases, the slope can never be negative.
Slope of displacement-time curve?
Velocity
Slope of displacement time graph?
positive or negative?
Can be both positive and negative!
Property of an object that resists acceleration?
Inertia. Property of object tending to maintain the state of rest or uniform motion.
Quantitative measure of inertia is?
Mass of object.
Force is measure and defined by which law?
Force is defined as the external effect which can change the state of motion or steady state of a body by law of inertia.
Force is measured by 2nd law of motion.
At what speed newtonian mechanics is valid?
Speeds much lower than speed of light.
lesser than 1% of speed of light.
lesser than 3000 km/s. = 3 × 10^6 m/s
lesser than 3 million m/s
What is quantity of motion called ?
Momentum
Unit of momentum
Kg m/s = N s
More general form of second law of motion?
F= m(Vf-Vi)/t F= del P/ del t
Collision of tennis balls?
Inelastic Collision
Hard ball collision with marble floor?
Elastic Collision
Collision can occur even when the objects don’t necessarily touch.
True or False?
True. e.g proton and helium nucleus
Billiard ball collision
Approximately Elastic. Would be truly elastic if produced no sound.
True elastic collisions occur in?
Atomic and sub atomic particles.
Thrust produced by the engine on the body?
mv (where m is mass per sec)
A typical rocket consumes about kg/s of fuel and and ejects the burnt gasses at speeds of over m/s.
10,000 kg/s
4000 m/s
Amount of fuel of a rocket?
80% of launch mass of rocket consists of fuel.
Trajectory of projectile?
Parabola
Things to remember in projectile motion
- Horizontal component of velocity remains constant
- a (x)= zero
- a(y)= g
- Velocity at maximum height= v(x)
Ballistic missile?
Unpowered and unguided.
For short ranges and flat Earth approximation.
Trajectory is called ballistic trajectory, is parabolic.
Dragless ballistic trajectory for spherical Earth should be elliptical.
Time of projectile is related to horizontal or vertical motion?
Vertical
Range = Height at angle?
tan^-1 (4)
Relation bw height and time
8H=gT^2
Relation bw height and range
R(max)=4H
