Question

If a net force of 7 N was constantly applied on 400 g object at rest, how long will it take to raise its velocity to 80 m/s?​

Answer 1

Answer:

Time taken to raise its velocity to 80 m/s is 4.57 sec.

Explanation:

Given:

• Force (F) = 7 N
• Mass (m) = 400 g = 0.4 kg

To find:

Time taken to raise its velocity to 80 m/s.

Solution:

We know that,

a = F/m

where,

• a = acceleration
• F = Force and
• m = mass

Now by substituting the values, we get

⟹ a = 7/0.4

⟹ a = = 17.5 m/s²

Now, t = (v – u)/a

We already know the value of v, u and a. So by keeping the values, we get

⟹ t = 4.57 sec

Answer 2

We have,

Magnitude of Force exerted = 7 N

Mass of object = 400 g = 0.4 kg

Initially, velocity = 0 m/s

Finally, velocity = 80 m/s

We know,

a = F/m

∴ a = (7 kg m/s²)/(0.4 kg) = 17.5 m/s²

Also,

v = u + at

⟹ t = v/t

⟹ t = 80 m/s ÷ 17.5 m/s²

⟹ t = 4.57 seconds.