A 3.5 kg body accelerates from rest to 20 m/s in 5 s. Calculate:

A its acceleration

B the force required.

A. a = (velocity change)/time = 20/5 = 4 m/s^2

B. F = m a

F=15000N

To calculate the acceleration of the body, we can use the formula:

Acceleration (a) = (Final velocity - Initial velocity) / Time

Given:
Mass (m) = 3.5 kg
Initial velocity (u) = 0 m/s
Final velocity (v) = 20 m/s
Time (t) = 5 s

A) Calculating the acceleration:
Acceleration (a) = (20 m/s - 0 m/s) / 5 s
Acceleration (a) = 20 m/s / 5 s
Acceleration (a) = 4 m/s²

Therefore, the acceleration of the body is 4 m/s².

B) To calculate the force required to accelerate the body, we can use Newton's second law of motion:

Force (F) = Mass (m) x Acceleration (a)

Given:
Mass (m) = 3.5 kg
Acceleration (a) = 4 m/s²

B) Calculating the force required:
Force (F) = 3.5 kg x 4 m/s²
Force (F) = 14 kg·m/s²
Force (F) = 14 Newtons (N)

Therefore, the force required to accelerate the body is 14 N.