Impulse is also known as the change in momentum of an object. Momentum has an equation of,
momentum = m x v
where m is mass and v is velocity. Therefore, impulse has a formula which is,
impulse = m x (v₂ - v₁)
Substituting the known values in the equation,
impulse = 975 kg x (3 m/s - 0.5 m/s)
impulse = 2437.5 kg m/s