## 20 terms · http://www.phys.uidaho.edu/documents/Practice%20Questions%20Exam%202.pdf?pid=89574&doc=1

### 5 m

1. A stone is thrown horizontally from the top of a cliff. One second after it has left your hand its vertical distance below the top of the cliff is

A) 5 m.

B) 10 m.

C) 15 m.

### about 5 m below the straight line

2. Throw an object upward at a 45 degree angle. With no gravity it will follow a straight-line path. But because of gravity, at the end of 1 second, it is

A) about 5 m below the straight line.

B) about 10 m below the straight line.

C) about 15 m below the straight line.

### remains constant

3. Roll a bowling ball off the edge of a table. As it falls, its horizontal component of velocity

A) decreases.

B) remains constant.

C) increases.

### as soon as it leaves the barrel

4. A bullet fired horizontally from a rifle begins to fall

A) as soon as it leaves the barrel.

B) after air friction reduces its speed.

C) neither of these

### 50 m/s

5. A projectile is launched vertically upward at 50 m/s. If air resistance is negligible, its speed upon returning to its starting point is

A) less than 50 m/s.

B) 50 m/s.

C) more than 50 m/s.

### freely falling around the earth

6. An Earth satellite is simply a projectile

A) freely falling around the earth.

B) floating motionless in space near the earth.

C) approaching the earth from outer space.

### atmosphere

7. Earth satellites are typically more than 100 km high so as to be above the Earthʹs

A) atmosphere.

B) gravitational field.

C) both of these

### it is not acted on by any horizontal forces

8. A projectile is fired horizontally in a region of no air resistance. The projectile maintains its horizontal component of velocity because

A) it is not acted on by any forces.

B) it is not acted on by any horizontal forces.

C) it has no vertical component of velocity to begin with.

D) the net force acting on it is zero.

E) none of these

### the dropped one

9. A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?

A) the dropped one

B) the fired one

C) Both hit at the same time.

### the fired one

10. A hunter on level ground fires a bullet at an angle of 2 degrees below the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?

A) the dropped one

B) the fired one

C) Both hit at the same time.

### 0.5 s

11. A bullet fired horizontally over level ground hits the ground in 0.5 second. If it had been fired with twice the speed in the same direction, it would have hit the ground in

A) less than 0.5 s.

B) more than 0.5 s.

C) 0.5 s.

### 1 g downward

12. An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward at an angle instead, its acceleration will be

A) 0 g.

B) 1 g downward.

C) 1 g upward.

D) larger than 1 g.

E) none of these

### 75 degrees

13. A projectile is launched at ground level an angle of 15 degrees above the horizontal and lands down range. What other projection angle for the same speed would produce the same down-range distance?

A) 30 degrees

B) 45 degrees

C) 50 degrees

D) 75 degrees

E) 90 degrees

### 40 degrees

14. A projectile is fired into the air at an angle of 50 degrees with the ground and lands on a target that is at the same level at which the projectile started. It will also land on the target if it is fired at an angle of

A) 40 degrees.

B) 45 degrees.

C) 55 degrees.

D) 60 degrees.

E) none of these

### 100

15. A gun with a muzzle velocity of 100 m/s is fired horizontally from a tower. Neglecting air resistance, how far downrange will the bullet be 1 second later?

A) 50 m

B) 98

C) 100

D) 490

E) none of these

### 30 degrees

16. Two projectiles are fired from ground level at equal speeds but different angles. One is fired at an angle of 30 degrees and the other at 60 degrees. The projectile to hit the ground first will be the one fired at (neglect air resistance)

A) 30 degrees.

B) 60 degrees.

C) Both hit at the same time.

### the same as it was at the top of its path

17. After a rock thrown straight up reaches the top of its path and then falls a short distance, its acceleration is (neglect air resistance)

A) greater than when it was a the top of its path.

B) less than when it was at the top of its path.

C) the same as it was at the top of its path.

### Nothing; theyʹre falling continuously all around the Earth

18. What prevents satellites such as a space shuttle from falling?

A) gravity

B) the absence of air drag

C) Nothing; theyʹre falling continuously all around the Earth.

### rise and fall back to the Earthʹs surface

19. A projectile is fired vertically from the surface of the Earth at 8 km/s. The projectile will

A) go into circular orbit about the Earth.

B) rise and fall back to the Earthʹs surface.

C) follow an uncertain path.

D) escape from the Earth.

### 283 km/h

20. The ground speed of an airplane that has an airspeed of 200 km/h when it is in a 200-km/h crosswind is

A) 0 km/h.

B) 200 km/h.

C) 283 km/h.

D) 400 km/h.

E) 1600 km/h.