an adult 68 kg cheetah can accelerate from rest to 20.1 m/s (45 mph) in 2.0 s. Assuming constant acceleration, (a) find the net external force causing this acceleration. (b) where does the force come from? that is, what exerts the force on the cheetah?
acceleration= changeinvelocity/time.
a= deltav/time
F=ma
Doesn't the ground exert force on the cheta?
i don't get the first equation explain more please
should i be using the equation you wrote for finding the net EXTERNAL force??
Yes. That is the force accelerating the cheeta.
i got 1366.8 N and i'm asked to round to SF would it be 1.3*10^2?
a= 20.1m/s /2= 10.05m/s^2
F= ma
How did you get that number 1366?
Now, rounding 1366.8 is not 1/3E2
E2 is 100. But you have other errors that need to be corrected.
i corrected it and i got 683.4 N, does that sounds right? if yes, would it be 6.8E-1?
To find the net external force causing the acceleration of the cheetah, we can use Newton's second law of motion. According to this law, the net force (F_net) acting on an object is equal to the mass (m) of the object multiplied by its acceleration (a).
First, we need to convert the cheetah's speed from meters per second to meters per second squared (m/s^2). Since acceleration is the rate at which speed changes over time, we can use the formula:
Acceleration (a) = Final velocity (v) - Initial velocity (u) / Time (t)
Given:
Initial velocity (u) = 0 m/s (since the cheetah starts from rest)
Final velocity (v) = 20.1 m/s
Time (t) = 2.0 s
Acceleration (a) = (20.1 m/s - 0 m/s) / 2.0 s
Acceleration (a) = 20.1 m/s / 2.0 s
Acceleration (a) = 10.05 m/s^2
Now, we can calculate the net force:
Net force (F_net) = mass (m) * acceleration (a)
Given:
Mass (m) = 68 kg
Acceleration (a) = 10.05 m/s^2
Net force (F_net) = 68 kg * 10.05 m/s^2
Net force (F_net) = 684.6 N
Therefore, the net external force causing the cheetah's acceleration is approximately 684.6 Newtons.
Now, moving on to the second part of the question, let's determine where the force comes from and what exerts it on the cheetah.
The force required to accelerate the cheetah comes from its muscles. The cheetah exerts force on the ground via its legs, which generates an equal and opposite force from the ground known as the reaction force. This reaction force propels the cheetah forward, causing it to accelerate according to Newton's third law of motion.
In summary, the force exerted on the cheetah comes from its own muscles, which push against the ground to create the necessary net external force for acceleration.