If a 55 kg ice skater is gliding along at 3. 5 m / s has her speed has dropped to 2.8 m / s in 5 s, the force required is - 7.7 N
a = v - u / t
a = Acceleration
v = Final velocity
u = Initial velocity
t = Time
u = 3.5 m / s
v = 2.8 m / s
t = 5 s
a = ( 2.8 - 3.5 ) / 5
a = - 0.7 / 5
a = - 0.14 m / s²
According to Newton's second law of motion,
F = m a
F = Force
m = Mass
a = Acceleration
m = 55 kg
F = 55 * - 0.14
F = - 7.7 N
The negative sign indicates that the force is applied on the opposite direction of motion
Therefore, the force required to drop the speed is - 7.7 N
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