Question

A cheetah of mass 68 kg can accelerate from rest to a speed of 20.1 m/s in 2.0 s. Assuming constant acceleration, what is the net force that causes this acceleration?
272 N
78 N
137 N
680 N

Answer 1

Answer:

680 N

Explanation:

We start by calculating the cheetah's acceleration knowing that goes from rest (0 speed) to 20.1 m/s in 2 seconds:

$a=\frac{v_f-v_1}{t} \\a=\frac{20.1-0}{2} =10.05 \frac{m}{s^2}$

Now we use the definition of force (F):

$F=m*a\\F=68 kg * 10.05 \frac{m}{s^2} =683.4 N$

Therefore the force that accelerates the cheetah is 683.4 Newtons which we can round to 680 N to match the fourth choice shown