Question

q 10
a 4 kg block is pushed a distance d = 5.0 m up a 30° incline, as shown above. what is the approximate change in the gravitational potential energy of the block-earth system when the block is at rest at the top of the incline, compared to at the bottom of the incline?
a 0 j
b 20 j
c 120 j
d 160 j
e 200 j

Explanation:

Step1: Identify height gain

The vertical height gained $h$ is 3.0 m (given in the diagram).

Step2: Use gravitational PE formula

Gravitational potential energy change is $\Delta U = mgh$.
Take $g = 10\ \text{m/s}^2$ (approximate value for simplicity), $m=4\ \text{kg}$, $h=3.0\ \text{m}$.
$\Delta U = 4 \times 10 \times 3.0$

Step3: Calculate the value

$\Delta U = 120\ \text{J}$

Answer:

C. 120 J