Lesson test: Motion in a plane

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Motion in a plane

1.[2p]
A bullet is fired horizontally at the same instant an identical bullet is dropped from the same height. Ignoring air resistance, which lands first?

They land together, because the vertical equation is the same for both and contains nothing horizontal

Correct

The dropped one, because it has no horizontal motion to slow it

The answer is: They land together, because the vertical equation is the same for both and contains nothing horizontal

The fired one, because it is moving faster

The answer is: They land together, because the vertical equation is the same for both and contains nothing horizontal

It depends on the muzzle speed

The answer is: They land together, because the vertical equation is the same for both and contains nothing horizontal

2.[2p]
A ball is launched from level ground at 20 m s⁻¹ at 45°. What is its range, in metres, with $g = 9.81$ m s⁻²?

CorrectNot quite: 40.8

3.[2p]
A ball is thrown from level ground at 30 m s⁻¹ at 60° above the horizontal. What is its greatest height, in metres?

CorrectNot quite: 34.4

4.[2p]
A car rounds a bend of radius 40 m at a steady 12 m s⁻¹. What is its centripetal acceleration, in m s⁻²?

CorrectNot quite: 3.6

5.[1p]
A body moving round a circle at constant speed has zero acceleration.

True

The answer is: False

False

Correct

6.[3p]
Which of these are true of a projectile launched over level ground with air resistance neglected?

Select all that apply

Its horizontal velocity component stays constant throughout the flight

Correct

Launch angles of 30° and 60° at the same speed give the same range

Correct

Its acceleration is $g$ downward at every point, including the top

Correct

Its speed is zero at the highest point of the flight

The answer is: Its horizontal velocity component stays constant throughout the flight, Launch angles of 30° and 60° at the same speed give the same range, Its acceleration is $g$ downward at every point, including the top

7.[2p]
An aircraft flies north with an airspeed of 200 m s⁻¹ while the wind blows from the west at 40 m s⁻¹. What is its ground speed, in metres per second?

CorrectNot quite: 204

8.[3p]
Match each situation to what the acceleration does to the velocity vector.

Acceleration parallel to velocity
Acceleration perpendicular to velocity
Acceleration at an oblique angle to velocity
Zero acceleration

changes neither
changes the speed only
changes both speed and direction
changes the direction only

Show the answer

Acceleration parallel to velocity: changes the speed only Acceleration perpendicular to velocity: changes the direction only Acceleration at an oblique angle to velocity: changes both speed and direction Zero acceleration: changes neither

9.[2p]
Put these steps of the derivation of $v^{2} / r$ in the order they are used.

The velocity vector turns through the same angle, keeping its length
Dividing by $Δ t$ gives an acceleration of $v^{2} / r$ towards the centre
For a small angle the change in velocity has magnitude $v Δ θ$
In time $Δ t$ the particle turns through $Δ θ = v Δ t / r$

Show the answer

a, b, c, d

1.[2p] A bullet is fired horizontally at the same instant an identical bullet is dropped from the same height. Ignoring air resistance, which lands first?

2.[2p] A ball is launched from level ground at 20 m s⁻¹ at 45°. What is its range, in metres, with g=9.81 m s⁻²?

3.[2p] A ball is thrown from level ground at 30 m s⁻¹ at 60° above the horizontal. What is its greatest height, in metres?

4.[2p] A car rounds a bend of radius 40 m at a steady 12 m s⁻¹. What is its centripetal acceleration, in m s⁻²?

5.[1p] A body moving round a circle at constant speed has zero acceleration.

6.[3p] Which of these are true of a projectile launched over level ground with air resistance neglected?

7.[2p] An aircraft flies north with an airspeed of 200 m s⁻¹ while the wind blows from the west at 40 m s⁻¹. What is its ground speed, in metres per second?

8.[3p] Match each situation to what the acceleration does to the velocity vector.

9.[2p] Put these steps of the derivation of v2/r in the order they are used.

1.[2p]
A bullet is fired horizontally at the same instant an identical bullet is dropped from the same height. Ignoring air resistance, which lands first?

2.[2p]
A ball is launched from level ground at 20 m s⁻¹ at 45°. What is its range, in metres, with $g = 9.81$ m s⁻²?

3.[2p]
A ball is thrown from level ground at 30 m s⁻¹ at 60° above the horizontal. What is its greatest height, in metres?

4.[2p]
A car rounds a bend of radius 40 m at a steady 12 m s⁻¹. What is its centripetal acceleration, in m s⁻²?

5.[1p]
A body moving round a circle at constant speed has zero acceleration.

6.[3p]
Which of these are true of a projectile launched over level ground with air resistance neglected?

7.[2p]
An aircraft flies north with an airspeed of 200 m s⁻¹ while the wind blows from the west at 40 m s⁻¹. What is its ground speed, in metres per second?

8.[3p]
Match each situation to what the acceleration does to the velocity vector.

9.[2p]
Put these steps of the derivation of $v^{2} / r$ in the order they are used.