The velocity-time graph of an object of mass 10 kg moving along a straight line is shown in the given figure. Calculate the force acting on the object by using the graph.

Given: Mass $m = 10$ kg

From the graph:

At $t = 0$ s, $v = 10$ m/s

At $t = 8$ s, $v = 30$ m/s

$$a = \frac{v-u}{t} = \frac{30-10}{8-0} = \frac{20}{8} = 2.5 \text{ m/s}^2$$

Using Newton's 2$^{nd}$ law

$$F = ma = 10 \times 2.5 = 25 \text{ N}$$

The force acting on the object is 25 N, in the direction of motion.