Projectile: Velocity and Ball
PROJECTILE MOTION
PRACTICE QUESTIONS (WITH ANSWERS)
* challenge questions
Q1.
A golfer practising on a range with an elevated tee
4.9 m above the fairway is able to strike a ball so that it leaves the club with a horizontal velocity of
20 m s–1. (Assume the acceleration due to gravity is
9.80 m s–2, and the effects of air resistance may be ignored unless otherwise stated.)
a b c d e
How long after the ball leaves the club will it land on the fairway?
What horizontal distance will the ball travel before striking the fairway?
What is the acceleration of the ball 0.5 s after being hit?
Calculate the speed of the ball 0.80 s after it leaves the club.
With what speed will the ball strike the ground? A1. a x = ut + 0.5at2 then 4.9 m = 0 + 0.5(9.8 m s–2)t2 and t = 1.0 s b x = (average speed)(time) = (20 m s–1)(1.0 s) =
20 m c The acceleration of the ball is constant at any time during its flight, and is equal to the acceleration due to gravity
= 9.8 m s–2 down d After 0.80 s, the ball has two components of velocity: vx = 20 m s–1 and vy = 0 + (9.8 m s–2)(0.80 s) = 7.84 m s–1
The speed of the ball at 0.80 s is given by:
[(20 m s–1)2 + (7.84 m s–1)2]½ = 21.5 m s–1
e
The ball will strike the ground 1.0 s after it is struck. Then vx = 20 m s–1 and vy = 0 + (9.8 m s–2)(1.0 s) = 9.8 m s–1
The speed of the ball at 1.0 s is given by:
[(20 m s–1)2 + (9.8 m s–1)2] ½ = 22.3 m s–1
Q2.
A bowling ball of mass 7.5 kg travelling at 10 m s–1 rolls off a horizontal table 1.0 m high. (Assume the acceleration due to gravity is 9.80 m s–2, and the effects of air resistance may be ignored unless otherwise stated.) a Calculate the ball’s horizontal velocity just as it strikes the floor. b What is the vertical velocity of the ball as it strikes the floor? c Calculate the velocity of the ball as it reaches the floor. d What time interval has elapsed between the ball leaving the table and striking the floor? e Calculate the horizontal distance travelled by the ball as it falls.
A2.
a The
PRACTICE QUESTIONS (WITH ANSWERS)
* challenge questions
Q1.
A golfer practising on a range with an elevated tee
4.9 m above the fairway is able to strike a ball so that it leaves the club with a horizontal velocity of
20 m s–1. (Assume the acceleration due to gravity is
9.80 m s–2, and the effects of air resistance may be ignored unless otherwise stated.)
a b c d e
How long after the ball leaves the club will it land on the fairway?
What horizontal distance will the ball travel before striking the fairway?
What is the acceleration of the ball 0.5 s after being hit?
Calculate the speed of the ball 0.80 s after it leaves the club.
With what speed will the ball strike the ground? A1. a x = ut + 0.5at2 then 4.9 m = 0 + 0.5(9.8 m s–2)t2 and t = 1.0 s b x = (average speed)(time) = (20 m s–1)(1.0 s) =
20 m c The acceleration of the ball is constant at any time during its flight, and is equal to the acceleration due to gravity
= 9.8 m s–2 down d After 0.80 s, the ball has two components of velocity: vx = 20 m s–1 and vy = 0 + (9.8 m s–2)(0.80 s) = 7.84 m s–1
The speed of the ball at 0.80 s is given by:
[(20 m s–1)2 + (7.84 m s–1)2]½ = 21.5 m s–1
e
The ball will strike the ground 1.0 s after it is struck. Then vx = 20 m s–1 and vy = 0 + (9.8 m s–2)(1.0 s) = 9.8 m s–1
The speed of the ball at 1.0 s is given by:
[(20 m s–1)2 + (9.8 m s–1)2] ½ = 22.3 m s–1
Q2.
A bowling ball of mass 7.5 kg travelling at 10 m s–1 rolls off a horizontal table 1.0 m high. (Assume the acceleration due to gravity is 9.80 m s–2, and the effects of air resistance may be ignored unless otherwise stated.) a Calculate the ball’s horizontal velocity just as it strikes the floor. b What is the vertical velocity of the ball as it strikes the floor? c Calculate the velocity of the ball as it reaches the floor. d What time interval has elapsed between the ball leaving the table and striking the floor? e Calculate the horizontal distance travelled by the ball as it falls.
A2.
a The