Newton’s Laws
True or False: An object at rest must have zero net force?
True
What is the SI unit of force?
Newton (N)
What is the weight of a 5 kg ball?
5×10=50N
What does Newton’s First Law state?
An object at rest stays at rest, and in motion stays in motion unless acted upon.
Name two forces on a box sliding down a ramp.
Gravity and friction.
A car goes from 0 to 20 m/s in 4 sec. What’s its acceleration?
5 m/s
Which law explains why pushing harder causes more acceleration?
Newton’s Second Law (F = ma)
What’s the net force if two equal forces act in opposite directions?
Zero (balanced)
A runner covers 100m in 10s. Average speed?
10 m/s
What is Newton’s Third Law?
Every action has an equal and opposite reaction.
What’s the difference between mass and weight?
Mass is the amount of matter in an object (measured in kg), and weight is the force of gravity on that mass (measured in newtons).
m = 3kg, a = 5 m/s². Find force.
F=15N
A rocket accelerates in space where there’s no air. Which of Newton’s laws explains how it moves?
Newton’s Third Law — the rocket pushes gas backward, and the gas pushes the rocket forward.
Difference between contact and non-contact forces?
Contact requires touch (friction); non-contact does not (gravity).
30N right, 10N left. Net force and Direction?
20N Right