7. A car accelerates uniformly from rest and reaches a speed of 20m/s in 10 seconds. What is its acceleration? (10 points) a) 1m/s^2 b 2m/s^2 3m/s^2 d) 4m/s^2

To find the acceleration of the car, we can use the formula for acceleration, which is given by:<br /><br />\[ a = \frac{{\Delta v}}{{\Delta t}} \]<br /><br />where \( a \) is the acceleration, \( \Delta v \) is the change in velocity, and \( \Delta t \) is the change in time.<br /><br />Given that the car starts from rest and reaches a speed of \( 20 \, \text{m/s} \) in \( 10 \) seconds, we can calculate the change in velocity as:<br /><br />\[ \Delta v = v_f - v_i \]<br /><br />where \( v_f \) is the final velocity and \( v_i \) is the initial velocity. Since the car starts from rest, the initial velocity is \( 0 \, \text{m/s} \). Therefore, the change in velocity is:<br /><br />\[ \Delta v = 20 \, \text{m/s} - 0 \, \text{m/s} = 20 \, \text{m/s} \]<br /><br />Now, we can calculate the acceleration:<br /><br />\[ a = \frac{{20 \, \text{m/s}}}{{10 \, \text{s}}} = 2 \, \text{m/s}^2 \]<br /><br />Therefore, the correct answer is:<br /><br />b) \( 2 \, \text{m/s}^2 \)