Exam questions

Question 1

A graph why y on the y-axis and the distance from the centre of the sun on the x-axis. 2 plots are placed one at (2,2) and another at (13,8). What would be on the y-axis to make this true

Answer 1

Time period of the planet

Question 2

A stress strain graph has a point (0,0) and a point (0.1,120) Where stress is measured in Mega pascals and the strain is 0.1%. What is the Youngs modules of this material

Answer 2

1.2 X 10^11 Pa

Question 3

An astronomer analyses the light from a distant galaxy.
One of the spectral lines in the spectrum observed from the galaxy has a wavelength of 610nm.
The same spectral line has a wavelength of 590nm when measured in the laboratory.

What is the speed of the galaxy

Answer 3

1.0 X 10^7 ms-1

Question 4

Explain what is meant by the ultimate tensile strength of a material

Answer 4

The maximum tensile stress a material can experience without breaking

Question 5

The resultant force on an object is 0.015N. The mass of an object is 1.2 X 10^-2 kg. Find the drag acting on the object

Answer 5

mg = 1.2X10^-2 X 9.81 or 0.118N

0.0156 = 0.118 - drag force

drag = 0.10N

Question 6

A student adds sand to a hollow ball that reaches terminal velocity.

Describe how the forces acting on the sand-filled ball at speed v compares with the forces acting on the hollow ball at this speed

v is terminal velocity

Answer 6

Drag is the same at a certain velocity

Resultant force is larger

Question 7

A mass is attached to a spring it obey simple harmonic motion. Explain the energy changes from the lowest point to the highest point.

Answer 7

• EPE decreases (from bottom to top)
• GPE increases (from bottom to top)

KE starts at zero, finishes at zero and max at the equilibrium point

Air gains thermal energy and the total energy decreases over time

Question 8

Explain why natural frequency and resonance can cause problems for engineers when designing suspended footbridge

Answer 8

• Bridge close to resonance if frequency is close to natural frequency of bridge
• (Close to resonance) giving larger amplitude which causes damage or other named consequence

Question 9

Calculate the internal energy of 1.3 moles of the gas at 250 centigrade.
Mass of gas molecules = 4.8 X 10^-26
root mean square speed = 671.6 ms-1

Answer 9

number of molecules is 1.3 X 6.02 X 10^23.

Mean KE = 3/2 X 1.38 X 10^-23 X (250+273)

= 8.5 X 10^3J

Question 10

There is an equal and opposite force of 350N on each side of a board. The distance between these forces is 5 X 10^-3m. Find the torque

Answer 10

350 X 5 X 10^-3

= 1.8 Nm

Question 11

p = 0.8 arcsecond

Calculate the distance using the conversion
1pc = 3.26ly

Answer 11

d = 1/0.8 = 1.25pc

1.25 X 3.26 = 4.11ly