Guess the Quantity
The rate at which an object changes its position.
Velocity
A car goes 60 km at 60 km/h and 60 km at 120 km/h. What is average speed?
80 km/h
Formula for speed in straight-line motion.
v = s / t
SI unit of force.
Newton (N)
Why do we lean forward when a bus suddenly stops?
Inertia / tendency to resist motion
The quantity representing how much matter is in an object.
Mass
A ball thrown up has zero velocity at the top. What is acceleration then?
Acceleration = 9,8 m/s² downward
Formula for gravitational potential energy.
PE = m g h
SI unit of energy.
Joule (J)
Why does a spinning ice skater spin faster when pulling her arms in?
Conservation of angular momentum / moment of inertia decreases
The force that resists motion between two surfaces.
Friction
Two resistors 4 Ω and 6 Ω in series. Find total resistance.
Rtotal= 4 + 6 = 10 Ω
Formula for kinetic energy of a moving object.
KE = ½ m v²
Unit of electric charge.
Coulomb (C)
Why does a ball roll slower on grass than on a smooth floor?
Because friction is greater on grass, it slows the ball down.
How much an object resists movement.
Inertia/Moment of Inertia
A wheel rotates, point at radius 0,5 m, ω = 4 rad/s. Find linear speed.
v = r ω = 0,5 × 4 = 2 m/s
Torque formula.
τ = F × r
Unit for power.
Watt (W)
Why does a passenger feel heavier when a lift accelerates upwards?
Due to increased normal force – apparent weight increases.
Energy due to motion.
Kinetic Energy
A pendulum of 2 m is lifted 0,5 m. Find speed at lowest point. (g=10 m/s^2)
v = √(2 g h) = √(2·10·0.5) ≈ 3.16 m/s
Formula for centripetal acceleration.
a = v² / r
Unit of electric current
Ampere (A)
Why does a boat float on water instead of sinking?
Because of Arhimed force acting upward, which balances weight.