A car is driven at a constant speed of 21 m/s (76km/h) down a road. The car's engine delivers 52 kW of power. Calculate the average force of friction that is resisting the motion of the car.
My thinking: Convert 52 kW to 5200 W. Force of friction = force applied because there is not a net force. Work = force x distance.
Thank you!!
Since Work = Force x Distance,
Power = Force x Velocity
Average force = Power/Velocity
= (52,000 kg m^2/s^3)/(21 m/s) = 2476 N
Ah, the wonderful world of physics! Let's calculate that average force of friction!
First, let's convert that magical power of 52 kW to watts. You indeed got it right! 52 kW is equal to 5200 W. Good job, my friend!
Now, let's focus on work. You are correct that work equals force times distance. However, since the car is traveling at a constant speed with no acceleration, the net work done on the car is zero (thanks to Newton's second law). Therefore, the work done by the engine is balanced out by the work done by the force of friction.
Since the car is moving at a constant speed, we can assume that the force of friction is equal in magnitude and opposite in direction to the force applied by the engine.
Now, since there is no acceleration, we know that the net force is zero. So, the force applied by the engine and the force of friction must be equal. You followin' me so far?
So, the average force of friction resisting the motion of the car is 5200 W.
But, of course, to make it more explicit, we can say the average force of friction is 5200 W divided by the speed of the car, which is 21 m/s. This gives us approximately 247.6 N.
There you have it, my friend! The average force of friction resisting the car's motion is about 247.6 Newtons.
Keep rolling with your physics questions, my friend!
To calculate the average force of friction resisting the motion of the car, you can use the relationship between power, force, and velocity.
1. Convert the power from kilowatts to watts:
52 kW = 52,000 W
2. The power delivered by the car's engine is equal to the work done by the force of friction, assuming no net force acting on the car.
Power = Force x Velocity
Rearranging the equation, we have:
Force = Power / Velocity
Substituting the given values:
Force = 52,000 W / 21 m/s
3. Calculate the force:
Force = 2,476.19 N
Therefore, the average force of friction resisting the motion of the car is approximately 2,476.19 Newtons.
To calculate the average force of friction that is resisting the motion of the car, you can use the following steps:
Step 1: Convert the power provided by the car's engine from kilowatts (kW) to watts (W).
Given that the car's engine delivers 52 kW, you can convert it to watts by multiplying by 1000:
52 kW * 1000 = 52000 W
So, the power provided by the car's engine is 52000 W.
Step 2: Determine the work done by the car's engine over a certain distance.
You mentioned that the car is driven at a constant speed of 21 m/s. To calculate the distance, you would need the time it took to travel that distance. However, since the question does not provide the time, we will assume a distance of 1 meter.
The work done by the car's engine can be calculated using the formula:
Work = Force x Distance
Since the car is moving at a constant speed, there is no net force, meaning the force applied (by the engine) is balanced by the force of friction. Therefore, the work done by the engine is equal to the work done against friction.
Step 3: Calculate the force of friction.
Rearranging the formula for work, we get:
Force of friction = Work / Distance
Using the values we have:
Force of friction = 52000 W / 1 m
Force of friction = 52000 N
Therefore, the average force of friction that is resisting the motion of the car is 52000 Newtons.