Grade 11 Projectile and Equilibrium Physics Flashcards (39 cards)

What two properties does a velocity vector have?

Magnitude and direction.

What is the formula for the horizontal velocity component at angle $\theta$?

$v_x = v \cos \theta$.

What is the formula for the vertical velocity component at angle $\theta$?

$v_y = v \sin \theta$.

What is the formula for velocity of B relative to A?

$\vec v_{B/A}=\vec v_B - \vec v_A$

Which velocity component determines crossing time for a boat perpendicular to river bank?

The crossing component.

Which velocity component determines downstream drift for a boat crossing a river?

The current velocity.

What is the formula for resultant speed of perpendicular velocities $v_1$ and $v_2$?

$v=\sqrt{v_1^2 + v_2^2}$

How do you calculate crossing time for a river width $w$ with perpendicular speed $v_\perp$?

$t=\frac{w}{v_\perp}$

How is downstream drift calculated when crossing a river?

$d = v_c t$

What condition must hold for a boat to cross straight with no downstream drift?

Its upstream velocity component equals the current speed.

What is the formula relating boat angle $\theta$, speed $v$, and current speed $v_c$ for no downstream drift?

$v \sin \theta = v_c$

What defines a horizontal projectile's initial velocities?

It has horizontal velocity and zero initial vertical velocity.

What is the formula for flight time of a horizontal projectile from height $h$?

$t=\sqrt{\frac{2h}{g}}$

How is the horizontal range $R$ of a horizontal projectile calculated?

$R=v_0\sqrt{\frac{2h}{g}}$

How does the horizontal velocity of a horizontal projectile change during flight?

It remains constant.

How does the vertical velocity $v_y$ of a horizontal projectile change over time?

It increases as $v_y=gt$.

What is the formula for total flight time of a projectile launched at speed $v_0$ and angle $\theta$?

$T=\frac{2v_0\sin\theta}{g}$

What is the formula for the time to reach maximum height in angled projectile motion?

$t_{max}=\frac{v_0\sin\theta}{g}$

How is the maximum height of a level-ground projectile expressed?

$H=\frac{v_0^2\sin^2\theta}{2g}$

At what launch angle does maximum range occur for fixed speed on level ground?

At 45° launch angle.

What is the moment of a force?

The turning effect of the force about a pivot.

What is the formula for the moment of a force using perpendicular distance?

$\tau=Fd$ where $d$ is the perpendicular distance from the pivot to the line of action.

How do you calculate the moment of a force at angle $\theta$ on a lever of length $L$?

$\tau=FL\sin\theta$.

What moment does a force have if its line of action passes through the pivot?

Zero moment about that pivot.

When is a body in translational equilibrium?

When the vector sum of all forces is zero.

What condition defines rotational equilibrium for a body?

The algebraic sum of its moments about a pivot is zero.

What is the formula for translational equilibrium?

$\sum \vec F=0$

What is the first step in solving a cable-equilibrium problem?

Resolve each tension into horizontal and vertical components.

What equations must be set to zero in cable-equilibrium problems?

The sums of horizontal and vertical forces.

What is the resultant magnitude of two perpendicular 20 m/s velocity components?

28.3 m/s.

What path does a package released from a level-flying plane follow relative to the ground?

A parabolic path.

What is the formula for the impact speed $v$ of a horizontal projectile?

$v=\sqrt{v_x^2+v_y^2}$

What is true about ranges for complementary launch angles with the same speed?

Their ranges are equal.

Which complementary launch angle produces greater maximum height?

The steeper angle produces greater maximum height.

What is the relation between maximum height, range, and launch angle for level-ground projectile?

$\tan\theta=\frac{4H}{R}$

What is the SI unit of moment and its usual positive direction?

The newton metre (N m), with counterclockwise moments usually positive.

What moment does a 5.0 N force produce when applied perpendicularly 0.40 m from a pivot?

2.0 newton metres.

What balances the weight of a sign hanging at rest?

The upward vertical components of the cable tensions.

What balances the horizontal components of cable tensions for a hanging sign?

Opposing horizontal components balance each other.