Question

Alex pushed a library cart (15.0kg) initially at rest with a constant force of 7.5N along a rough horizonta surface. The wagon accelerated at 0.25 m/s². How much work was done over 3.5sec?

Answer 1

Answer:

• 11.5 Joules

Explanation:

Given that : Alex pushed a library cart (15.0kg) initially at rest with a constant force of 7.5N along a rough horizonta surface. The wagon accelerated at 0.25 m/s².

The formula to calculate the work done given by,

• $W = Fd$

Where ,

• W is work done
• F is force (7.5 N)
• d is displacement

First let's calculate the displacement (d)

Displacement (d) can be calculated by using the kinematics eqn.

$d = ut +\dfrac{1}{2} at^2$

Where,

• u is initial velocity (0 m/s as Alex pushed the library cart initially at rest)
• a is acceleration (0.25 m/s²)
• t is time (3.5 seconds)

Plugging the required values,

$d = 0(3.5) + \dfrac{1}{2} (0.25)(3.5)^2$

$d = 0.125 \times 12.25$

$d = 1.53 \: m$

Now, Calculating the Work done :

• W = Fd
• W = 7.5 × 1.53
• W = 11.5 Joules

Hence, the work done is 11.5 Joules