QUARTER 4 GRADE 9

Projectile motion is a form of motion experienced by an object or particle projected into the air. Which of the following solely affects the motion of the object for it to be called a projectile?

• A. mass

• B. gravity

• C. contact force

• D. air resistance

If a free-falling ball is equipped with a speedometer, by how much would its speed-reading increase for every second?

• A. 0 m/s

• B. 8.9 m/s

• C. 9.8 m/s

• D. 10.8 m/s

Zed is playing with a ball on top of a building but the ball falls and hits the ground after 2.6 seconds. What is the final velocity of the ball just before it hits the ground and how high is the building?

• A. -23 m/s, 30 m

• B. -24 m/s, 31 m

• C. -25 m/s, 32 m

• D. -26 m/s, 33 m

A baseball is thrown vertically upward into the air. What is the instantaneous speed of the ball at its highest point?

• A. 0 m/s

• B. 0.8 m/s, up

• C. 9.8 m/s, up

• D. 9.8 m/s, down

Which of the following is an example of a projectile?

• A. A spinning top

• B. A descending airplane

• C. A javelin being thrown from the level ground

• D. A man riding in a basket under a hot air balloon

A soccer player kicks a ball with an initial velocity of 15.0 meters per second at an angle of 30.0° above the horizontal. What is the magnitude of the horizontal component of the ball’s initial velocity (vi_x)?

• A. 5.0 m/s

• B. 7.5 m/s

• C. 9.8 m/s

• D. 13.0 m/s

The horizontal motion of the projectile is the result of the tendency of any object in motion to remain in motion at constant velocity. Ignoring air resistance, why would the horizontal velocity of a projectile does not change after the initial thrust of the object?

• A. The force of gravity keeps it constant.

• B. There is no horizontal force acting upon it.

• C. There is a horizontal force that keeps its velocity constant.

• D. The horizontal motion of the projectile is dependent on its vertical

  motion.

The Law of Conservation of Momentum states that the total momentum of a system does not change if _________________. Which of the following words or phrases complete the statement?

• A. there are external forces acting on it.

• B. there are internal forces acting on it.

• C. no net internal forces are acting on it.

• D. no net external forces are acting on it.

In Newtonian mechanics, linear momentum, translational momentum, or simply momentum is the product of the mass and velocity of an object. How can you increase the linear momentum of an object with constant mass?

• A. By increasing its velocity

• B. By decreasing its velocity

• C. By making the velocity zero

• D. By keeping the velocity constant

Cars are equipped with padded dashboards. In collision, how safer are padded dashboards than non-padded dashboards?

• A. It will decrease an occupant’s impulse.

• B. It will increase an occupant’s impulse.

• C. It will increase the impact of time and decrease the impact of force.

• D. It will decrease the impact of time and increase the impact of force.