Question

John is going to use a rope to pull his sister Laura across the ground in a sled through the snow. He is pulling horizontally with a constant force of 400 N. John and manages to get the sled going from 0 to 4 m/s in 5 s. The force due to friction on the sled is 310 N. What is the mass of Laura and the sled combined?

Answer 1

Answer:

The mass of Laura and the sled combined is 887.5 kg

Explanation:

The total force due to weight of Laura and friction on the sled can be calculated as follows;

$F_T = F_L+F_S$

     = (400 + 310) N

     = 710 N

From Newton's second law of motion, "the rate of change of momentum is directly proportional to the applied force.

$F_T = \frac{(M_L+M_S)V}{t}$

where;

$M_L$ is mass of Laura and

$M_S$ is mass of sled

Mass of Laura and the sled combined is calculated as follows;

$(M_L+M_S) = \frac{F_T*t}{V}$

given

V = Δv = 4-0 = 4m/s

t = 5 s

$(M_L+M_S) = \frac{710*5}{4}\\\\(M_L+M_S) = 887.5 kg$

Therefore, the mass of Laura and the sled combined is 887.5 kg