Physical Quantities & Measurement Techniques (Cambridge O Level Physics)

A student places 8 similar coins in a pile, as shown in Fig. 1.1.

The height of the pile of coins is 2.4 cm.

Calculate the average thickness of one coin.

average thickness = .................................................. cm 

Fig. 1.2 shows the pile of coins, a measuring cylinder and a beaker containing some water.

Describe how the student can measure the volume of one of the coins using the set-up shown in Fig. 1.2.

An object of weight W is suspended by two ropes from a beam, as shown in Fig. 1.1.

Fig. 1.1

The tensions in the ropes are 45.6 N and 81.1 N, as shown.

Using a scale of 1 cm = 10 N, make a scale drawing to show the resultant force of the two tensions.

Clearly label the resultant force.

Using your scale diagram from part (a), find the magnitude and direction of the resultant force.

magnitude of resultant force = ....................................

direction of resultant force = .................................... 

State the value of W.

W = .................................... 

State another vector quantity other than a type of force.

State the definition of a vector quantity.

Extended Only

A list of vector quantities and their SI units are given in the following table.

Complete the information missing from the table.

Extended Only

A horizontal force of 136 N to the right, and a vertical downward force of 54 N act on an object perpendicularly to one another.

By use of a scale diagram (not by calculation) determine the magnitude of the resultant force.

magnitude of resultant force = .................................... 

Using the information from part (c), determine the direction of the resultant force. 

direction of resultant force = .................................... from the horizontal

A bucket of water hangs from a rope attached to a pole as shown in Fig. 1.1.

Fig. 1.1

The tension force,  = 31 N and the ropes are perpendicular to one another.

Calculate the magnitude of the downward force acting on the bucket of water.

magnitude of downward force = .................................... 

State the name of the downward force acting on the bucket.

Weight is a vector quantity. Name one other vector quantity.

The bucket has a mass of 0.65 kg.

Calculate the mass of the water in the bucket.

A teacher investigates the reaction time of five students. A 0.50 m ruler is held above the hand of a student before being allowed to fall. The arrangement is shown in Fig. 3.1.

As soon as the ruler falls the student closes their hand, catching the ruler. The further the ruler falls, the greater the reaction time of the student. The results obtained are shown in Fig. 3.2.

Using the results shown in Fig. 3.2, calculate the average distance that the ruler drops.

List the students in order of their reaction times, with the shortest reaction time at the top of the table. One has been done for you.

Calculate the reaction time.

  
reaction time = ...................................................... s 

Fig. 1.1 shows a large tank containing water. The tank leaks. Drops of water fall from the tank.

The drops hit the ground at a regular rate.

She uses a stopwatch and repeats the procedure three times. Fig. 1.2 shows each stopwatch reading.

Another student measures the average time taken for a drop of water to fall from the tank to the ground. The time taken is 1.6 s.

Calculate the average speed of this drop of water.

average speed = ................................................... m/s 

A student has a piece of metal that has an irregular shape. The weight of the metal is 3.0 N.

Calculate the mass of the metal.

mass = ..................................................... kg 

Fig. 2.1 shows the piece of metal, a measuring cylinder and a beaker containing water.

Two students are discussing mass and weight.

Student 1 claims that a person's weight will be different on Mars than it is on Earth.

Describe the difference between mass and weight, and explain whether you agree with Student 1.

Identify the vector quantities.

Tick all the boxes that apply.

displacement

distance

speed

velocity

Two forces act at right angles to one another: a 35 N force acts to the right and a 42 N force acts downward.

Construct a scale diagram showing the effect of these two forces, and label the resultant force as X.

Use the scale 10 N = 1 cm

Calculate the magnitude and direction of the resultant force of the forces acting from part (c)

magnitude of resultant force = ....................................

direction of resultant force = .................................... to the horizontal