Which one of the following machines is used to lift a car to change a flat tyre?Question 8Answera.Wedgeb.Screw jackc.Claw hammerd.Ramp

To lift a car safely for changing a flat tire, the best choice among the options given is the screw jack.

Explanation:

1. Wedge: This is a tool used primarily for splitting or lifting but is not designed for lifting heavy objects such as a car.
2. Screw Jack: This is specifically designed to lift heavy loads by turning a screw mechanism. It is commonly used in automotive applications.
3. Claw Hammer: This tool is intended for driving nails and removing them; it is not suitable for lifting.
4. Ramp: While ramps can be used to drive a car up for access to the underside, they do not lift a car vertically in the same way as a jack.

Conclusion:

The screw jack is the appropriate machine for lifting a car to change a flat tire because it is designed for that specific purpose, making it the best choice in this scenario.