Question

In: Physics

A driver spots a huge pothole ahead and hits her brakes, and the car accelerates at...

A driver spots a huge pothole ahead and hits her brakes, and the car accelerates at -20 m/s ^2. Please pay attention to the mass of the car because two experts changed it to 1.250kg and it is 1,250kg. Also explain the math. Thanks.

A. If the car’s mass is 1,250 kg, what is the net force on it?

B. What applies the force on the car that causes it’s deceleration?

C. If the driver’s mass is 60 kg, what is the net force on her?

D. What applies the force on the driver that causes her deceleration?

Solutions

Expert Solution

A. Net force = mass * acceleration = 1250*20 = 25000 N or 25 KN

B. When the breaks are hit a pressure chamber releases the break fluid. The pressure fluid on reaching the break pads make it touch the revolving rotor. The friction force between the break pad and the rotor slows down the rotor and causes the de deceleration.

C. Force on driver = 60*20 = 1200 N or 1.2 KN.

D. The cause of the driver's deceleration is the same as the driver is in the inertial frame of the car. But when the brake is applied suddently there is not enough time to stop the motion of drivers and hence the driver feels a forward force. This is the reason seat belts are necessary.


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