The velocity-time graph of an object of mass m = 120 50 g is shown in figure. Observe the graph carefully and answer the following questions. (a) Calculate the force on the object in time interval 0 to 3 s. (b) Calculate the force on the object in the time interval 6 to 10 s. (c) Is there any time interval in which no force acts on the object? Justify your answer.

(a) Acceleration during interval 0 to 3s

𝑎₁ = {𝑣−𝑢 \over 𝑡}  = {120−0\over3} = 40𝑚/s ²

Given mass, m = 50 g  = {50\over1000} kg

∴ Force, 𝐹₁ = ma₁ = ({50\over1000}) ×40  2N

(b) Acceleration during interval 6 to 10 s

𝑎₂ = {𝑉_2−𝑉_1 \over 𝑡}  = {0 − 120\over ( 10−6)}

= – {120\over4} = – 30 m/s ²

Force, 𝐹₂ = ma₂ = 50\over1000 × (-30) = – 1.5 N

(c) During time interval 3 to 6 s, the velocity of object is constant, so in this time interval, acceleration is zero and hence force, F (= ma) is zero.]