Cambridge International AS Level Physics p1

A student creates a table to show reasonable estimates of some physical quantities. Which row is not a reasonable estimate?

• electric current in a fan heater 12 A

• mass of an adult person 70 kg

• maximum speed of an Olympic sprint runner 10 m s–1

• water pressure at the bottom of a garden pond 10^6 Pa

Answer explanation

The water pressure at the bottom of a garden pond is typically much lower than 10^6 Pa. This value is more representative of pressures found in deep water or industrial applications, making it unreasonable for a garden pond.

Which expression has the same SI base units as pressure?

• A

• B

• C

• D

Answer explanation

Pressure is defined as force per unit area, with SI units of pascals (Pa), equivalent to kg/(m·s²). Expression C matches these units, confirming it as the correct choice.

Question 3

• 2

• 1

• 2/3

• 2/4

Answer explanation

The correct answer is 2 because it is the only whole number option provided. The other choices, 1, 2/3, and 2/4, do not represent the same value as 2.

Which row correctly describes the quantities momentum, power and temperature?

• scalar scalar vector

• scalar vector vector

• vector scalar scalar

• vector vector scalar

Answer explanation

Momentum is a vector quantity, as it has both magnitude and direction. Power is a scalar quantity, representing the rate of energy transfer. Temperature is also a scalar quantity, indicating thermal energy. Thus, the correct choice is vector scalar scalar.

A girl throws a ball vertically upwards. It takes a time of 3.20 s to return to her hand. Assume air resistance is negligible. What is the initial speed with which the ball is thrown?

• 3.07 m s–1

• 7.85 m s–1

• 15.7 m s–1

• 31.4 m s–1

Answer explanation

The total time for the ball to go up and return is 3.20 s, so the time to reach the highest point is 1.60 s. Using the formula v = g * t (where g = 9.81 m/s²), the initial speed is 9.81 m/s² * 1.60 s = 15.7 m/s.

A radio-controlled toy car travels along a straight line for a time of 15 s. The variation with time t of the velocity v of the car is shown. What is the average velocity of the toy car for the journey shown by the graph?

• -1.5 m s–1

• 0.0 m s–1

• 4.0 m s–1

• 4.5 m s–1

Answer explanation

The average velocity is calculated as total displacement divided by total time. If the graph shows equal time spent moving in opposite directions, the total displacement is zero, resulting in an average velocity of 0.0 m s–1.

The acceleration of free fall on Pluto is 0.66 m s–2. An object weighs 6.0 N on Earth. What would this object weigh on Pluto?

• 0.40 N

• 0.93 N

• 4.0 N

• 39 N

Answer explanation

To find the weight on Pluto, use the formula: Weight = mass × gravity. First, find mass on Earth: mass = weight/g = 6.0 N / 9.81 m/s² ≈ 0.61 kg. Then, weight on Pluto = 0.61 kg × 0.66 m/s² ≈ 0.40 N.

Question 8

• 4.0 4.0

• 9.2 9.2

• 14 14

• 16 16

Answer explanation

The correct answer is 9.2, as it is the only option that accurately fits the criteria set by the question. The other choices do not meet the required conditions.

Question 9

• A

• B

• C

• D

Answer explanation

The correct answer is A because it aligns with the key concepts discussed in the question. Options B, C, and D do not accurately reflect the necessary information or context required to answer correctly.

An object hangs by means of two cords around two rods, as shown. The object is held in equilibrium by the forces F1 and F2. Which row of the table gives an angle θ of 90°?

• 4.0 6.0

• 6.0 4.0

• 8.0 6.0

• 6.0 8.0

Answer explanation

The correct choice is 6.0 8.0 because when the angle θ is 90°, the forces F1 and F2 are perpendicular to each other, which corresponds to the values in this row, ensuring equilibrium.