Question

which situation describes an object that has no unbalanced force acting on it?
(1) an apple in free fall
(2) a satellite orbiting earth
(3) a hockey puck moving at constant velocity across ice
(4) a laboratory cart moving down a frictionless 30.° incline
11.
a 0.50 - kilogram puck sliding on a horizontal shuffleboard court is slowed to rest by a frictional force of 1.2 newtons. what is the coefficient of kinetic friction between the puck and the surface of the shuffleboard court?
(1) 0.24
(2) 0.42
(3) 0.60
(4) 4.1

Explanation:

Step1: Calculate the normal force

On a horizontal surface, the normal force \(F_N\) equals the weight of the object. Using the formula \(F_N = mg\), where \(m = 0.50\space kg\) and \(g= 9.8\space m/s^{2}\).
\(F_N=0.50\times9.8 = 4.9\space N\)

Step2: Use the formula for kinetic friction

The formula for kinetic friction is \(F_f=\mu_kF_N\). We know \(F_f = 1.2\space N\) and \(F_N = 4.9\space N\). Rearranging for \(\mu_k\), we get \(\mu_k=\frac{F_f}{F_N}\)
\(\mu_k=\frac{1.2}{4.9}\approx0.24\)

Answer:

(1) \(0.24\)