This is a suggested answer to the GCE O Level Pure Physics examination, year 2014, Paper 1, multiple choice question 7.
The question stated that a cable of crane is used to lift a load. The following information were provided:
- Mass of load =500kg
- Weight of load =5000N
- The Cable exerts a force of 7500N
The student is required to calculate the acceleration of the load.
Answer is A . That is, 5 m/s2
When the load is being lifted up, there is a resultant force. The resultant force is the result of the two forces:
Weight of the load, given as:
And force exerted on the load by the cable which is given as: 7500N.
The resultant force is therefore 7500N-5000N =2500N
However, the formula of resultant force is:
Resultant Force, F = Mass x acceleration
hence, the acceleration, a = 2500N/500kg
= 5 m/s2