William Heathcote Solutions for Chapter: Function, Exercise 13: Summative assessment

To test an electric motor,a student devises the apparatus shown in the diagram :

The student proposes changing the mass that the motor tries to lift and timing it takes for the mass to be lifted $1 \mathrm{m}$.  When the motor is switched is on $500 \mathrm{g}$ accelerates upwards with the speed about $0.05 \mathrm{m} {\mathrm{s}}^{-1}$. Acceleration of the mass is $0.51 \mathrm{m} {\mathrm{s}}^{-2}$. What is the tension in the string during this acceleration (in Newton).

To test an electric motor,a student devises the apparatus shown in the diagram :

The student proposes changing the mass that the motor tries to lift and noting the time it takes for the mass to be lifted $1 \mathrm{m}$.  When the motor is switched on $500 \mathrm{g}$ accelerates upwards with the speed about $0.05 \mathrm{m} {\mathrm{s}}^{-1}$. Acceleration of the mass is $0.51 \mathrm{m} {\mathrm{s}}^{-2}$. After first $0.1 \mathrm{s}$ the mass travels upwards at a constant speed. Explain why this shows that the tension must have the same magnitude as the weight of $500 \mathrm{g}$ mass.

To test an electric motor,a student devises the apparatus shown in the diagram :

The student proposes changing the mass that the motor tries to lift and timing it takes for the mass to be lifted $1 \mathrm{m}$.  When the motor is switched is on $500 \mathrm{g}$ accelerates upwards with the speed about $0.05 \mathrm{m} {\mathrm{s}}^{-1}$. Acceleration of the mass is $0.51 \mathrm{m} {\mathrm{s}}^{-2}$. Calculate the work done (in Joules) in lifting the mass of $500 \mathrm{g}$ through $1 \mathrm{m}$. 

The current through the motor while lifting $500 \mathrm{g}$ is $0.17 \mathrm{A}$. Calculate the resistance (in ohms) of the motor when lifting the mass.

The student notices that as the mass is increased, the current in the circuit also increases. Explain why the current increases?

Many industrial processes now use automated robots to carry out various tasks. Some manufacturers are increasing the number of robots used in the production lines. Describe the advantages of using robots in the industry.

Many industrial processes now use automated robots to carry out various tasks. Some manufacturers are increasing the number of robots used in the production lines.Some manufacturers are removing some robots in the factory and employing people to do these jobs. Explain the advantages of using human workforce rather than robots.

For centuries machines have been used to make certain tasks easier.Pick one machine, explain what it does and how it makes that task easier. Try to use simple scientific terms effectively.