Answer:
19.6 m/s
Explanation:
The parameters given are:
Mass M = 20 Kg
Force F = 285 N
Angle Ø = 30 degree
Time t = 4 seconds
Coefficient of friction = 0.72
At the plane, the weight of the box will be mgsinØ
Resolving forces at the plane, we will have:
MgsinØ + Fr = F
Where Fr = frictional force.
Fr = F - mgsinØ
Substitute all the parameters into the formula
Fr = 285 - 20 × 9.8 sin30
Fr = 285 - 98
Fr = 187 N
But for the box moving toward the top of the plane,
F - Fr = ma
Where a = V/t
Substitute all the parameters involved into the formula
285 - 187 = 20 ( V/4)
98 = 5V
V = 98/5
V = 19.6 m/s
Therefore, the speed with which the box is moving is 19.6 m/s
