Answer:
The formula for calculating weight is F = m × 9.8 m/s2, where F is the object's weight in Newtons (N) and m is the object's mass in kilograms.
The basic relationship between voltage, resistance and current of an electrical device is given by Ohm's law:

where
V is the voltage
I is the current
R is the resistance
The hot plate in our problem is connected to a source of V=120 V and it has a resistance of

, therefore we can rearrange the previous equation to calculate the current through the device:
<u>Answer:</u> The mass of the second car is 12666.7 kg
<u>Explanation:</u>
To calculate the mass of car, we use the equation of law of conservation of momentum, which is:

where,
= mass of car 1 = 9500 kg
= Initial velocity of car 1 = 14 m/s
= mass of car 2 = ? kg
= Initial velocity of car 2 = 0 m/s
= Final velocity = 6.0 m/s
Putting values in above equation, we get:

Hence, the mass of the second car is 12666.7 kg
Given the speed of the sound in the problem which is 1 mile per 5 seconds.
The speed is calculated by:
Speed = distance/time = (1mi/5s) (1610 m/1mi) = 300 m/s
Note that only 1 significant figure is given which is 5 second and so only 1 significant figure is justified in the result. The speed of sound is 343 m/s. therefore the rule of thumb is fairly close.