Newton's Laws
Which of Newton's laws states that an object at rest stays at rest unless acted upon by an unbalanced force?
Newton's First Law of Motion.
What force pulls objects toward Earth?
Gravity.
What is the term for a change in an object's speed or direction?
Acceleration.
What force causes a parachutist to fall toward the ground?
Gravity.
What unit is used to measure force?
Newtons (N).
Which of Newton's laws explains that acceleration depends on force and mass?
Newton's Second Law of Motion.
What force opposes motion between two surfaces touching each other?
Friction.
What two quantities determine an object's acceleration according to Newton's Second Law?
Net force and mass.
Which Newton's law explains why releasing an inflated balloon causes it to fly away?
Newton's Third Law of Motion.
Two forces of 5 N and 3 N push an object in the same direction. What is the net force?
8 N in the direction of the pushes.
Which of Newton's laws states that every action has an equal and opposite reaction?
Newton's Third Law of Motion.
What type of force is used when a person pushes a box across the floor?
Applied force.
What happens to a moving object if no unbalanced force acts on it?
It continues moving at a constant velocity in a straight line.
Why should passengers wear seat belts according to Newton's First Law?
Because inertia causes passengers to continue moving forward when the car suddenly stops. Seat belts exert a force to stop them safely.
A box has 4 N pushing right and 6 N pushing left. What is the net force and direction?
2 N to the left.
A passenger moves forward when a car suddenly stops. Which law explains why?
Newton's First Law, because the passenger's body tends to remain in motion due to inertia.
A ball rolls down a hill and speeds up. Which force causes it to accelerate, and why?
Gravity. A component of gravitational force pulls the ball downhill, increasing its speed.
If the same net force is applied to a light object and a heavy object, which will accelerate faster? Explain.
The lighter object, because less mass results in greater acceleration when the net force is the same.
A car brakes suddenly and its tires slide across the road. What force helps slow the car, and how?
Friction between the tires and road acts against the car's motion, slowing it down.
A box has 15 N pushing right and 15 N pushing left. Calculate the net force and explain what happens to its motion.
0 N. The forces are balanced, so the box will remain at rest or continue moving at constant velocity.
Explain how Newton's Third Law allows a rocket to launch into space.
The rocket pushes exhaust gases downward, and the gases exert an equal and opposite force upward on the rocket.
Two identical marbles roll down identical ramps. Marble A travels 15 cm, while Marble B travels 8 cm on cotton. Explain the difference.
Cotton creates greater friction or rolling resistance, slowing Marble B more quickly. Marble A travels farther because it experiences less resistance.
A 5 kg object experiences a net force of 20 N. Calculate its acceleration and explain the formula.
4 m/s². Using F = ma, divide 20 N by 5 kg to get 4 m/s².
A roller coaster reaches the top of a hill and begins moving downhill without its motor pushing it. Explain which force causes the roller coaster to speed up and how Newton's Second Law applies to its motion.
Gravity pulls the roller coaster downhill, causing it to accelerate. According to Newton's Second Law (F = ma), an unbalanced net force causes acceleration. As the roller coaster travels downhill, gravity causes its speed to increase.
A 10 kg box has 80 N pushing right and 30 N pushing left. Calculate the net force and acceleration, including direction.
Net force = 80 − 30 = 50 N right. Acceleration = F ÷ m = 50 ÷ 10 = 5 m/s² to the right.