A ball of mass 2kg travelling in a straight line at 4ms^-1 is acted on by a force of 3N acting in the direction of motion for 5 seconds. What is the speed of the ball after 5 seconds?
vf=vi+at but a=force/mass
a = 3÷2= 1.5
vf=4+1.5×5=
vf=4+7.5
vf=11.5m/s^-1
Is this correct? If not please can you correct it for me
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You are on the right track, but there is a mistake in your calculation. The equation vf = vi + at is correct, but the value you calculated for acceleration (a) is incorrect.
Acceleration (a) is equal to the force (F) divided by the mass (m). In this case, the force (F) is given as 3N and the mass (m) is given as 2kg. So, the correct value for acceleration (a) is:
a = F/m = 3N / 2kg = 1.5 m/s^2
Now, you can use the equation vf = vi + at to calculate the final velocity (vf):
vf = 4 m/s + (1.5 m/s^2) × 5 s
vf = 4 m/s + 7.5 m/s
vf = 11.5 m/s
So, the correct answer is that the speed of the ball after 5 seconds is 11.5 m/s.
Your calculation is incorrect. Let's correct it step by step:
1. Find the acceleration (a) using the formula a = force / mass:
a = 3 N / 2 kg
a = 1.5 m/s²
2. Now, use the equation of motion v = u + at, where:
v = final velocity (speed) of the ball
u = initial velocity of the ball (given: 4 m/s)
a = acceleration (1.5 m/s²)
t = time (given: 5 s)
v = 4 m/s + (1.5 m/s² × 5 s)
v = 4 m/s + 7.5 m/s
v = 11.5 m/s
Therefore, the correct answer is that the speed of the ball after 5 seconds is 11.5 m/s.