Question

A steel cable lying flat on the floor drags a 20 kg block across a horizontal, frictionless floor. A 110 N force applied to the cable causes the block to reach a speed of 4.2 m/s in a distance of 2.0 m
What is the mass of the cable?
Express your answer to two significant figures and include the appropriate units.

Answer 1

Answer:

The mass of the cable is 4.94 kg                                                                                                                                                                            

Explanation:

It is given that,

Mass of the block, m = 20 kg

Force applied to the cable, F = 110 N

Speed of the block, v = 4.2 m/s

Distance, d = 2 m

Let a is the acceleration of the block. It can be calculated using the third equation of motion as :

$v^2-u^2=2ad$

$(4.2)^2-(0)^2=2a\times 2$

$a=4.41\ m/s^2$

Let m' is the mass of the cable. It can be calculated using the second law of motion as :

$m'=\dfrac{F}{a}-m$

$m=\dfrac{110\ N}{4.41\ m/s^2}-20$

m = 4.94 kg

So, the mass of the cable is 4.94 kg. Hence, this is the required solution.