1. A 6.0-N force and an 8.0-N force act concurrently on a point. As the angle between these forces increases from 0° to 90°, the magnitude of their resultant
(3) remains the same
2. A car increases its speed from 9.6 m/s to 11.2 m/s in 4.0 s. The average acceleration of the car during this 4.0-second interval is
(1) 0.40 m/s2 (3) 2.8 m/s2
(2) 2.4 m/s2 (4) 5.2 m/s2
3. What is the speed of a 2.5-kilogram mass after it has fallen freely from rest through a distance of 12 m?
(1) 4.8 m/s (3) 30. m/s
(2) 15 m/s (4) 43 m/s
4. A machine launches a tennis ball at an angle of 25° above the horizontal at a speed of 14 m/s. The ball returns to level ground. Which combination of changes must produce an increase in time of flight of a second launch? (1) decrease the launch angle and decrease the ball’s initial speed (2) decrease the launch angle and increase the ball’s initial speed (3) increase the launch angle and decrease the ball’s initial speed (4) increase the launch angle and increase the ball’s initial speed
5. A plane flying horizontally above Earth’s surface at 100. m/s drops a crate. The crate strikes the ground 30.0 s later. What is the magnitude of the horizontal component of the crate’s velocity just before it strikes the ground? [Neglect friction.]
(1) 0 m/s (3) 294 m/s
(2) 100. m/s (4) 394 m/s
6. A woman with horizontal velocity v1 jumps off a dock into a stationary boat. After landing in the boat, the woman and the boat move with velocity v2. Compared to velocity v1, velocity v2 has
(1) the same magnitude and the same direction
(2) the same magnitude and opposite direction
(3) smaller magnitude and the same direction
(4) larger magnitude and the same direction
7. A ball attached to a string is moved at constant speed in a horizontal circular path. A target is located near the path of the ball as shown in the diagram.
At which point along the ball’s path should the string be released, if the ball is to hit the target?
(1) A (2) B(3) C(4) D
8. Which object has the greatest inertia?
(1) a 5.0-kg object moving at a speed of 5.0 m/s
(2) a 10.-kg object moving at a speed of 3.0 m/s
(3) a 15-kg object moving at a speed of 1.0 m/s
(4) a 20.-kg object at rest
9. As an astronaut travels from the surface of Earth to a position that is four times as far away from the center of Earth, the astronaut’s
(1) mass decreases
(2) mass remains the same
(3) weight increases
(4) weight remains the same
10. A 0.15-kilogram baseball moving at 20. m/s is stopped by a catcher in 0.010 second. The average force stopping the ball is
(1) 3.0 × 10–2 N (3) 3.0 × 101 N
(2) 3.0 × 100 N (4) 3.0 × 102 N
11. The diagram below shows a 4.0-kilogram object accelerating at 10. m/s2 on a rough horizontal surface.
What is the magnitude of the frictional force Ff acting on the object?
(1) 5.0 N (3) 20. N
(2) 10. N (4) 40. N
12. What is the magnitude of the force needed to keep a 60.-N rubber block moving across level, dry asphalt in a straight line at a constant speed of 2.0 m/s? The coefficient of kinetic friction is 0.67.
(1) 40. N (3) 60. N
(2) 51 N (4) 120 N
13. What is the acceleration due to gravity at a location where a 15.0-kg mass weighs 45.0 N?
(1) 675 m/s2 (3) 3.00 m/s2
(2) 9.81 m/s2 (4) 0.333 m/s2
14. As a car is driven south in a straight line with decreasing speed, the acceleration of the car must be
(1) directed northward(2) directed southward
(3) zero(4) constant, but not zero
15. A baseball dropped from the roof of a tall building takes 3.1 seconds to hit the ground. How tall is the building? [Neglect friction.]
(1) 15 m (3) 47 m
(2) 30. m (4) 94 m
16. Which object has the greatest inertia?
(1) a falling leaf
(2) a softball in flight
(3) a seated high school student