Physics Motion

scalar quantity

Magnitude only

vector quantity

Magnitude and Direction

Motion in 2 dimensions

Objects move in the horizontal and vertical direction

Projectile Motion

An object launched and moves under gravities influence in 2 dimensions

Vertical component of velocity

Changes due to gravity. Decreases on the way up, Zero at the maximum height, and increases on the way down.

Horizontal component of velocity

Constant during the entire trajectory.

Why is the optimal angle 45

• Sh = Vh*t = vcosx*t = V0cosx((2v0sinx)/g)

• The range increased when the horizontal component of velocity and time of flight are maximised

• Increasing the launch angle above 45 will increase the time of flight, but decrease the horizontal component of velocity

• Decreasing the launch angle below 45 will decrease the time of flight, but increase the horizontal component of velocity

• 45 provides a balance between maximising the horizontal component of velocity and time of flight

Air Resistance

Opposes vertical and horizontal motion and is proportional to acceleration. Range, height, and time of flight reduces

Fd formula (drag force)

1/2pACv²

Terminal Velocity

At low speeds, the initial force is small anTid the ball accelerates vertically downward in the direction of the net force due to the weight of the object. At higher speeds, air resistance is equal to the weight and the object falls with constant velocity

Time of flight formula

2V0sinx/g

Max height formula

(V0sinx)²/2g or V0cosx((2V0sinx)/g)

Range formula

V0²sin2x/g

Momentum

Combined impact of mass and velocity. Property of moving objects.

Conservation of momentum

Total momentum is conserved in an isolated system. An isolated system is unaffected by external forces. If the vector sum of external forces is zero, it is called and isolated system. Momentum is constant

Propulsion

Push forward or drive an object forward.

Explain the propulsion in rockets using the law of conservation of momentum

The rocket and cargo are in an isolated system. The combustion of fuel produces exhaust gases that gain momentum to the rear of the rocket. To conserve momentum, the rocket gains the same magnitude of momentum as the exhaust gases in the opposite direction, causing it to accelerate in its direction of motion

Explain the propulsion in ion thrusters using the law of conservation of momentum

The ion thruster produces positively charged ions that are accelerated to the rear of the spacecraft. To conserve momentum, the spacecraft gains an equal magnitude of momentum in the opposite direction to the ions which causes it to accelerate in its direction of motion.

Solar Sailing

Solar photons transfer momentum when they are absorbed or reflected from a solar sail. The transfer of momentum causes the solar sail to accelerate to a very high speed over time.

What happens in photon absorption of solar sails

To conserve momentum, the solar sail gains a magnitude of momentum equal to the initial momentum of the photon in the same direction.

What happens in photon reflection of solar sails

To conserve momentum, the solar sail gains a magnitude of momentum equal to twice the initial momentum of the photon in the same direction.