Question

Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts a force of 75.0 N, the second a force of 95.0 N, friction is 12.0 N, and the mass of the third child plus wagon is 21.0 kg.
(c) Calculate the acceleration.
m/s2
(d) What would the acceleration be if friction is 20.0 N?

Answer 1

Answer:

Value of acceleration in each case is  $7.52\ m/s^2 \ and \ 7.14\ m/s^2.$

Explanation:

According to newton's law :

$F_{net} = ma$       ...equation 1.

In the given case, $F_{net}=$ Force by both the children - Friction force .

$F_{net} = (75+95)-12=158\ N.$

Putting value of F in equation 1.

$a=\dfrac{F_{net}}{m}=\dfrac{158}{21}=7.52\ m/s^2.$

Now, if friction force = 20 N.

Therefore, $F_{net}=(75+95)-20=150\ N.$

Putting value of F and a in equation 1.

$a=\dfrac{F_{net}}{m}=\dfrac{150}{21}=7.14\ m/s^2.$

Hence , this is the required solution.