A net force of 3.7 × 10^3 N acts on an object for 3.95 s. During this time, an object accelerates from rest to a velocity of 40.0 km/h. What is the mass of this object?

Question

A net force of 3.7 × 10^3 N acts on an object for 3.95 s. During this time, an object accelerates from rest to a velocity of 40.0 km/h. What is the mass of this object?

Answer 1

Find the magnitude of the acceleration, then divide the magnitude of the force by the magnitude of the acceleration.

m = |F| / |a|

|F| = 3.7 x 10³ N

|a| = |v₂ - v₁| / t

v₂ - v₁ = (40.0 - 0) km/hr

Convert to m/s.

v₂ - v₁ = 40.0 (1000 meters) / (3600 sec) = ? m/s

|a| = |v₂ - v₁| / t = [40.0 (1000 meters) / (3600 sec)] / (3.95 sec) = ? m/s²

Finally,

m = |F| / |a|

You have everything you need; now plug in the numbers and finish from here. The result will be in units of kg.