Subtopic 2.3 Projectile Motion

The path of a projectile motion is

• Linear

• Parabolic

• Constant

• Straight

At maximum height, the vertical component of the velocity (Vy) is equal to

• Vx = Ux = U cos teta

• Vy = 0

• Vy = Uy = U sin teta

• Vy= Ux-gt

Which of the following angle gives a projectile with maximum range?

• 0

• 45

• 60

• 90

A ball is thrown upward at an angle 45^o from a rooftop. Which physical quantity remain constant?

• velocity

• impulse

• y-component of the acceleration

• kinetic energy

what is the speed of the object at point A?

• 0.57u

• 0.67u

• 0.87u

• 1.07u

sketch the direction of the velocity,V and its components, V_x and V_y at point A.

Answer explanation

The direction of the velocity must follow the path of the motion. meanwhile the x component, v_x directed to the right and y-component,v_y is directed downward.

The y-component of the acceleration, a_y is equal to 9.81 ms^-2 and is directed downward. True or false?

• true

• false

the horizontal component of the acceleration, ax is always equal to zero. why?

• because the direction of the velocity varies.

• because the x-component of the velocity is always constant, u_x = v_x

• because object changes its direction.

• because its affected by the action of gravity

Answer explanation

initial and final velocity in the x-component, u_x=v_x is always constant throughout the motion. hence a_x = 0

based on the figure, which concept is incorrect?

• S_y = +300 m

• u_y = 0

• u = u_x = 50 ms-1

• S_x = U_x. t

Answer explanation

S_y must be - 300 m because its direction is downward.

based on the figure, which concept is incorrect?

• u_x = 15 cos 30^o

• u_y = 15 sin 30^o

• v_y = u_x -gt

Answer explanation

the correct equation is

v_y = u_y - gt.

x and y 'don't talk' to each other