Question

A delivery company has unloaded a 21 kg crate in your driveway. The coefficient of static friction between the crate and the driveway surface is μs = 0.70. The coefficient of kinetic friction is μk = 0.60. In order to move the crate, you apply a horizontal force of magnitude F by pushing on it. As a result, the crate slides with an acceleration of 4.0 m/s2. What is the force F?

Answer 1

F = 207.48 N

Step-by-step explanation:

given,

mass of crate = 21 kg

μs = 0.70

μk = 0.60

a = 4 m/s²

normal reaction force

N = m g

`F_(net)=F-f_k`

`F_(net)=F-\mu_k N`

`F_(net)=F-\mu_k mg`

`ma=F-\mu_k mg`

`F =m(a + \mu_k g)`

`F =21 (4 + 0.6 * 9.8)`

F = 207.48 N