Hydraulic brakes are based on

Options

A. Pascal's law
B. Torricelli's law
C. Newton's law
D. Boyle's law

Explanation

### Step-by-Step Solution:

1. **Understanding Hydraulic Brakes**: Hydraulic brakes are a system used in vehicles to stop or slow down the motion. They utilize a fluid-filled system to transmit force from the brake pedal to the brake pads.

2. **Identifying Components**: In hydraulic brakes, there are two pistons: one with a larger cross-sectional area and another with a smaller cross-sectional area. The larger piston is usually connected to the brake pedal, while the smaller piston is connected to the brake pads.

3. **Applying Force**: When the driver presses the brake pedal, a force (F1) is applied to the larger piston (with area A). This creates pressure in the hydraulic fluid.

4. **Pressure Calculation**: The pressure exerted by the fluid is given by the formula:
\[ P = \frac{F_1}{A} \]
where \(P\) is the pressure, \(F_1\) is the force applied, and \(A\) is the area of the piston.

5. **Pressure Transmission**: According to the principles of hydraulics, this pressure is transmitted equally throughout the fluid in all directions. Therefore, the pressure at the smaller piston (with area A2) can be expressed as:
\[ P = \frac{F_2}{A_2} \]
where \(F_2\) is the force exerted by the smaller piston.

6. **Applying Pascal's Law**: Pascal's law states that when pressure is applied to a confined fluid, the pressure change occurs throughout the fluid without loss. This means:
\[ \frac{F_1}{A} = \frac{F_2}{A_2} \]
This relationship allows the hydraulic system to amplify the force applied at the brake pedal, enabling the vehicle to stop effectively.

7. **Conclusion**: Since hydraulic brakes operate based on the principle that pressure is transmitted equally in all directions in a fluid, they are based on Pascal's law.

### Final Answer:
Hydraulic brakes are based on **A. Pascal's law**.

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