Copy each passage into your book and fill in the numbered gaps using the word bank. Then check your answers. ← All topics
1. Scalars, vectors and types of force (C+S)
A scalar quantity has magnitude only, while a (1)______ quantity has magnitude and (2)______. Speed is a scalar, but velocity is a vector. Forces are vectors and can be shown by (3)______ whose length shows the size of the force. (4)______ forces act only when objects touch, such as friction, air resistance and tension. Non-contact forces act at a distance, such as (5)______, electrostatic and magnetic forces.
Word bank: arrows · contact · direction · gravitational · vector
Check your answers
1 vector · 2 direction · 3 arrows · 4 Contact · 5 gravitational
2. Weight and resultant force (C+S)
Weight is the force acting on an object due to (1)______. It is calculated using W = mg and measured with a (2)______ (a newtonmeter). The weight of an object can be considered to act at a single point called its centre of (3)______. When several forces act on an object, they can be replaced by a single (4)______ force that has the same effect. If the forces are balanced, the resultant force is (5)______.
Word bank: calibrated spring-balance · gravity · mass · resultant · zero
Check your answers
1 gravity · 2 calibrated spring-balance · 3 mass · 4 resultant · 5 zero
3. Work done and springs (C+S)
Work is done when a force causes an object to move through a (1)______: W = Fs. One joule of work is done when a force of 1 N moves an object 1 m. Work done against friction causes a rise in the (2)______ of the object. When a spring is stretched, the extension is directly (3)______ to the force applied (F = ke), as long as the limit of proportionality isn’t exceeded. If an object returns to its original shape when the force is removed, it has been (4)______ deformed; if not, it has been (5)______ deformed.
Word bank: distance · elastically · inelastically · proportional · temperature
Check your answers
1 distance · 2 temperature · 3 proportional · 4 elastically · 5 inelastically
4. Moments and pressure in fluids (S only)
The turning effect of a force is called its (1)______: M = Fd, where d is the perpendicular distance from the (2)______. If an object is balanced, the total clockwise moment equals the total (3)______ moment. Pressure in a fluid acts at right angles to any surface. The pressure increases with (4)______ because there is a greater weight of fluid above. An object in a fluid feels an upward force called (5)______; it floats if this equals its weight.
Word bank: anticlockwise · depth · moment · pivot · upthrust
Check your answers
1 moment · 2 pivot · 3 anticlockwise · 4 depth · 5 upthrust
4b. Pressure in liquids and upthrust (S only)
A fluid can be a liquid or a (1)______. The pressure in a fluid causes a force (2)______ (at right angles) to any surface. Pressure = force ÷ (3)______, measured in pascals. (HT) The pressure due to a column of liquid is p = hρg, so it increases with the (4)______ and with the (5)______ of the liquid. A submerged object feels more pressure on its bottom surface than its top, which creates an upward resultant force called (6)______. An object floats if the upthrust equals its weight – objects that are less (7)______ than the fluid float.
Word bank: area · dense · density · depth · gas · normal · upthrust
Check your answers
1 gas · 2 normal · 3 area · 4 depth · 5 density · 6 upthrust · 7 dense
4c. Atmospheric pressure (S only)
The atmosphere is a thin layer of (1)______ around the Earth. It gets less (2)______ with increasing altitude. Air molecules colliding with a surface create atmospheric (3)______. The higher you go, the fewer air molecules there are (4)______ a surface, so the weight of air above it is (5)______. This means atmospheric pressure (6)______ as height increases.
Word bank: above · air · decreases · dense · pressure · smaller
Check your answers
1 air · 2 dense · 3 pressure · 4 above · 5 smaller · 6 decreases
4d. Levers and gears (S only)
Simple levers and simple gear systems can both be used to transmit the (1)______ effects of forces. A lever acts as a force (2)______: a small force applied a (3)______ distance from the pivot can produce a large force close to the pivot. In a gear system, when a small gear drives a (4)______ gear, the larger gear turns more (5)______ but with a bigger moment.
Word bank: large · larger · multiplier · rotational · slowly
Check your answers
1 rotational (turning) · 2 multiplier · 3 large · 4 larger · 5 slowly
4e. Free body diagrams and resolving forces (C+S, HT)
A free body diagram shows all the (1)______ acting on one object, drawn as arrows from its centre. (HT) Forces can be added using a scale drawing to find the (2)______ force. A single force can be (3)______ into two components acting at right angles to each other. If the forces on an object are balanced, the vector diagram forms a (4)______ shape and the object is in (5)______.
Word bank: closed · equilibrium · forces · resolved · resultant
Check your answers
1 forces · 2 resultant · 3 resolved · 4 closed · 5 equilibrium
5. Speed, velocity and motion graphs (C+S)
Distance is how far an object moves; (1)______ is the distance in a straight line from start to finish, with a direction. Typical speeds are about 1.5 m/s for walking and 330 m/s for (2)______ in air. On a distance–time graph, the (3)______ gives the speed. Acceleration is the rate of change of (4)______: a = Δv ÷ t. On a velocity–time graph, the gradient gives the acceleration and the (5)______ under the graph gives the distance travelled.
Word bank: area · displacement · gradient · sound · velocity
Check your answers
1 displacement · 2 sound · 3 gradient · 4 velocity · 5 area
6. Newton’s laws (C+S)
Newton’s first law: if the resultant force on an object is zero, a stationary object stays (1)______ and a moving object keeps moving at the same speed in the same direction. Newton’s second law: acceleration is directly proportional to the resultant force and inversely proportional to the (2)______ (F = ma). (HT) The tendency of an object to stay at rest or keep moving uniformly is called (3)______. Newton’s third law: when two objects interact, the forces they exert on each other are (4)______ and (5)______.
Word bank: equal · inertia · mass · opposite · stationary
Check your answers
1 stationary · 2 mass · 3 inertia · 4 equal · 5 opposite
7. Terminal velocity (C+S)
When an object starts to fall, its (1)______ is bigger than the air resistance, so it accelerates. As its speed increases, the air resistance (2)______, so the resultant force and the acceleration get smaller. Eventually the air resistance (3)______ the weight, the resultant force is zero, and the object falls at a steady speed called its (4)______ velocity. Opening a parachute increases the surface (5)______, so the air resistance increases and the object slows down.
Word bank: area · equals · increases · terminal · weight
Check your answers
1 weight · 2 increases · 3 equals · 4 terminal · 5 area
8. Stopping distance (C+S)
Stopping distance = (1)______ distance + braking distance. A typical reaction time is between 0.2 s and 0.9 s. Reaction time is increased by tiredness, drugs, alcohol and (2)______. Braking distance is increased by wet or icy roads and worn tyres or brakes, which reduce (3)______. When the brakes are applied, work is done by friction, transferring energy from the car’s (4)______ store to the thermal store of the brakes. Large decelerations can make the brakes (5)______ or cause loss of control.
Word bank: distractions · friction · kinetic · overheat · thinking
Check your answers
1 thinking · 2 distractions · 3 friction · 4 kinetic · 5 overheat
9. Momentum (C+S, HT)
Momentum = mass × (1)______ (p = mv), measured in kg m/s. In a (2)______ system, the total momentum before an event is equal to the total momentum after – this is conservation of momentum. (S only) The force on an object equals its rate of change of (3)______. Seatbelts, airbags and crumple zones increase the (4)______ taken to stop, which reduces the rate of change of momentum and so reduces the (5)______.
Word bank: closed · force · momentum · time · velocity
Check your answers
1 velocity · 2 closed · 3 momentum · 4 time · 5 force
