Horizontal Projectiles

Which best describes the horizontal motion of a projectile, assuming no air resistance?

• Acceleration of -10 m/s²

• Acceleration of -5 m/s²

• An increasing acceleration every second

• Constant velocity

Which best describes the vertical motion of a projectile, assuming no air resistance?

• Acceleration of about -10 m/s²

• Accelerations of about -5 m/s²

• An increasing acceleration every second

• Constant velocity

A marble traveling at 3 m/s rolls off the edge of a 1 m high table. What is its initial vertical speed?

• -10 m/s

• 0 m/s

• -3 m/s

• -15 m/s

A soccer ball is kicked horizontally off a cliff. What information is needed to find the time to fall?

• The height of the cliff

• The initial speed of the ball

• The mass of the ball

• All of these

Tags

NGSS.HS-PS2-4

A player kicks a ball across the field. At the very top, what is the acceleration of the ball?

• It is accelerating to the right

• There is no acceleration at the top

• 10 m/s² up

• 10 m/s² down

A cannon is fired horizontally with the speed of 4 m/s from a 5.0 m tall tower. How much time will it take until the projectile hits the ground?

• 0.5 s

• 1.0 s

• 2.0 s

• 5.0 s

Answer explanation

Use dy = 1/2 gt^2 to calculate the time.

If a ball is launched horizontally at 40 m/s from a bridge, what will be the magnitude of its horizontal velocity after 3 seconds?

• 30 m/s

• 40 m/s

• 50 m/s

• 70 m/s

Answer explanation

Horiz. speed remains the same.

What is the relationship between motion in the x and y-dimensions?

• If x is greater, then y is greater

• If x is greater, then y is less

• There is no relationship; independent

A cannonball is launched horizontally at 50 m/s from an 80 m tall cliff. How far will it go (horizontally) before hitting the ground?

• 100 m

• 200 m

• 400 m

• 800 m

Answer explanation

Use dy = 1/2 gt^2 to find the time first. Do not plug in the vx here.

After, use dx = vx times t to find the Range!

Two spheres, A and B, are simultaneously projected horizontally from the top of a tower. Sphere A has a horizontal speed of 40. meters per second and Sphere B has a horizontal speed of 20. meters per second.
Which statement best describes the time required for the spheres to reach the ground and the horizontal distance they travel?   [Neglect friction and assume the ground is level.]

• Both spheres hit the ground at the same time and at the same distance from the base of the tower.

• Both spheres hit the ground at the same time, but sphere A lands twice as far as sphere B from the base of the tower.

• Both spheres hit the ground at the same time, but sphere B lands twice as far as sphere A from the base of the tower.

• Sphere A hits the ground before sphere B, and sphere A lands twice as far as sphere B from the base of the tower